Added bundler as default gems. Revisit [Feature #12733]

  * bin/*, lib/bundler/*, lib/bundler.rb, spec/bundler, man/*:
    Merge from latest stable branch of bundler/bundler repository and
    added workaround patches. I will backport them into upstream.
  * common.mk, defs/gmake.mk: Added `test-bundler` task for test suite
    of bundler.
  * tool/sync_default_gems.rb: Added sync task for bundler.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65509 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

58 files changed, 8740 insertions, 0 deletions

diff --git a/spec/bundler/bundler/bundler_spec.rb b/spec/bundler/bundler/bundler_spec.rb
new file mode 100644
index 0000000000..194d6752b2
--- /dev/null
+++ b/spec/bundler/bundler/bundler_spec.rb
@@ -0,0 +1,490 @@
+# encoding: utf-8
+# frozen_string_literal: true
+
+require "bundler"
+require "tmpdir"
+
+RSpec.describe Bundler do
+  describe "#load_gemspec_uncached" do
+    let(:app_gemspec_path) { tmp("test.gemspec") }
+    subject { Bundler.load_gemspec_uncached(app_gemspec_path) }
+
+    context "with incorrect YAML file" do
+      before do
+        File.open(app_gemspec_path, "wb") do |f|
+          f.write strip_whitespace(<<-GEMSPEC)
+            ---
+              {:!00 ao=gu\g1= 7~f
+          GEMSPEC
+        end
+      end
+
+      it "catches YAML syntax errors" do
+        expect { subject }.to raise_error(Bundler::GemspecError, /error while loading `test.gemspec`/)
+      end
+
+      context "on Rubies with a settable YAML engine", :if => defined?(YAML::ENGINE) do
+        context "with Syck as YAML::Engine" do
+          it "raises a GemspecError after YAML load throws ArgumentError" do
+            orig_yamler = YAML::ENGINE.yamler
+            YAML::ENGINE.yamler = "syck"
+
+            expect { subject }.to raise_error(Bundler::GemspecError)
+
+            YAML::ENGINE.yamler = orig_yamler
+          end
+        end
+
+        context "with Psych as YAML::Engine" do
+          it "raises a GemspecError after YAML load throws Psych::SyntaxError" do
+            orig_yamler = YAML::ENGINE.yamler
+            YAML::ENGINE.yamler = "psych"
+
+            expect { subject }.to raise_error(Bundler::GemspecError)
+
+            YAML::ENGINE.yamler = orig_yamler
+          end
+        end
+      end
+    end
+
+    context "with correct YAML file", :if => defined?(Encoding) do
+      it "can load a gemspec with unicode characters with default ruby encoding" do
+        # spec_helper forces the external encoding to UTF-8 but that's not the
+        # default until Ruby 2.0
+        verbose = $VERBOSE
+        $VERBOSE = false
+        encoding = Encoding.default_external
+        Encoding.default_external = "ASCII"
+        $VERBOSE = verbose
+
+        File.open(app_gemspec_path, "wb") do |file|
+          file.puts <<-GEMSPEC.gsub(/^\s+/, "")
+            # -*- encoding: utf-8 -*-
+            Gem::Specification.new do |gem|
+              gem.author = "André the Giant"
+            end
+          GEMSPEC
+        end
+
+        expect(subject.author).to eq("André the Giant")
+
+        verbose = $VERBOSE
+        $VERBOSE = false
+        Encoding.default_external = encoding
+        $VERBOSE = verbose
+      end
+    end
+
+    it "sets loaded_from" do
+      app_gemspec_path.open("w") do |f|
+        f.puts <<-GEMSPEC
+          Gem::Specification.new do |gem|
+            gem.name = "validated"
+          end
+        GEMSPEC
+      end
+
+      expect(subject.loaded_from).to eq(app_gemspec_path.expand_path.to_s)
+    end
+
+    context "validate is true" do
+      subject { Bundler.load_gemspec_uncached(app_gemspec_path, true) }
+
+      it "validates the specification" do
+        app_gemspec_path.open("w") do |f|
+          f.puts <<-GEMSPEC
+            Gem::Specification.new do |gem|
+              gem.name = "validated"
+            end
+          GEMSPEC
+        end
+        expect(Bundler.rubygems).to receive(:validate).with have_attributes(:name => "validated")
+        subject
+      end
+    end
+
+    context "with gemspec containing local variables" do
+      before do
+        File.open(app_gemspec_path, "wb") do |f|
+          f.write strip_whitespace(<<-GEMSPEC)
+            must_not_leak = true
+            Gem::Specification.new do |gem|
+              gem.name = "leak check"
+            end
+          GEMSPEC
+        end
+      end
+
+      it "should not pollute the TOPLEVEL_BINDING" do
+        subject
+        expect(TOPLEVEL_BINDING.eval("local_variables")).to_not include(:must_not_leak)
+      end
+    end
+  end
+
+  describe "#which" do
+    let(:executable) { "executable" }
+    let(:path) { %w[/a /b c ../d /e] }
+    let(:expected) { "executable" }
+
+    before do
+      ENV["PATH"] = path.join(File::PATH_SEPARATOR)
+
+      allow(File).to receive(:file?).and_return(false)
+      allow(File).to receive(:executable?).and_return(false)
+      if expected
+        expect(File).to receive(:file?).with(expected).and_return(true)
+        expect(File).to receive(:executable?).with(expected).and_return(true)
+      end
+    end
+
+    subject { described_class.which(executable) }
+
+    shared_examples_for "it returns the correct executable" do
+      it "returns the expected file" do
+        expect(subject).to eq(expected)
+      end
+    end
+
+    it_behaves_like "it returns the correct executable"
+
+    context "when the executable in inside a quoted path" do
+      let(:expected) { "/e/executable" }
+      it_behaves_like "it returns the correct executable"
+    end
+
+    context "when the executable is not found" do
+      let(:expected) { nil }
+      it_behaves_like "it returns the correct executable"
+    end
+  end
+
+  describe "configuration" do
+    context "disable_shared_gems" do
+      it "should unset GEM_PATH with empty string" do
+        env = {}
+        expect(Bundler).to receive(:use_system_gems?).and_return(false)
+        Bundler.send(:configure_gem_path, env)
+        expect(env.keys).to include("GEM_PATH")
+        expect(env["GEM_PATH"]).to eq ""
+      end
+    end
+  end
+
+  describe "#rm_rf" do
+    context "the directory is world writable" do
+      let(:bundler_ui) { Bundler.ui }
+      it "should raise a friendly error" do
+        allow(File).to receive(:exist?).and_return(true)
+        allow(bundler_fileutils).to receive(:remove_entry_secure).and_raise(ArgumentError)
+        allow(File).to receive(:world_writable?).and_return(true)
+        message = <<EOF
+It is a security vulnerability to allow your home directory to be world-writable, and bundler can not continue.
+You should probably consider fixing this issue by running `chmod o-w ~` on *nix.
+Please refer to http://ruby-doc.org/stdlib-2.1.2/libdoc/fileutils/rdoc/FileUtils.html#method-c-remove_entry_secure for details.
+EOF
+        expect(bundler_ui).to receive(:warn).with(message)
+        expect { Bundler.send(:rm_rf, bundled_app) }.to raise_error(Bundler::PathError)
+      end
+    end
+  end
+
+  describe "#mkdir_p" do
+    it "creates a folder at the given path" do
+      install_gemfile <<-G
+        source "file://#{gem_repo1}"
+        gem "rack"
+      G
+
+      Bundler.mkdir_p(bundled_app.join("foo", "bar"))
+      expect(bundled_app.join("foo", "bar")).to exist
+    end
+
+    context "when mkdir_p requires sudo" do
+      it "creates a new folder using sudo" do
+        expect(Bundler).to receive(:requires_sudo?).and_return(true)
+        expect(Bundler).to receive(:sudo).and_return true
+        Bundler.mkdir_p(bundled_app.join("foo"))
+      end
+    end
+
+    context "with :no_sudo option" do
+      it "forces mkdir_p to not use sudo" do
+        expect(Bundler).to receive(:requires_sudo?).and_return(true)
+        expect(Bundler).to_not receive(:sudo)
+        Bundler.mkdir_p(bundled_app.join("foo"), :no_sudo => true)
+      end
+    end
+  end
+
+  describe "#user_home" do
+    context "home directory is set" do
+      it "should return the user home" do
+        path = "/home/oggy"
+        allow(Bundler.rubygems).to receive(:user_home).and_return(path)
+        allow(File).to receive(:directory?).with(path).and_return true
+        allow(File).to receive(:writable?).with(path).and_return true
+        expect(Bundler.user_home).to eq(Pathname(path))
+      end
+
+      context "is not a directory" do
+        it "should issue a warning and return a temporary user home" do
+          path = "/home/oggy"
+          allow(Bundler.rubygems).to receive(:user_home).and_return(path)
+          allow(File).to receive(:directory?).with(path).and_return false
+          allow(Etc).to receive(:getlogin).and_return("USER")
+          allow(Dir).to receive(:tmpdir).and_return("/TMP")
+          allow(FileTest).to receive(:exist?).with("/TMP/bundler/home").and_return(true)
+          expect(FileUtils).to receive(:mkpath).with("/TMP/bundler/home/USER")
+          message = <<EOF
+`/home/oggy` is not a directory.
+Bundler will use `/TMP/bundler/home/USER' as your home directory temporarily.
+EOF
+          expect(Bundler.ui).to receive(:warn).with(message)
+          expect(Bundler.user_home).to eq(Pathname("/TMP/bundler/home/USER"))
+        end
+      end
+
+      context "is not writable" do
+        let(:path) { "/home/oggy" }
+        let(:dotbundle) { "/home/oggy/.bundle" }
+
+        it "should issue a warning and return a temporary user home" do
+          allow(Bundler.rubygems).to receive(:user_home).and_return(path)
+          allow(File).to receive(:directory?).with(path).and_return true
+          allow(File).to receive(:writable?).with(path).and_return false
+          allow(File).to receive(:directory?).with(dotbundle).and_return false
+          allow(Etc).to receive(:getlogin).and_return("USER")
+          allow(Dir).to receive(:tmpdir).and_return("/TMP")
+          allow(FileTest).to receive(:exist?).with("/TMP/bundler/home").and_return(true)
+          expect(FileUtils).to receive(:mkpath).with("/TMP/bundler/home/USER")
+          message = <<EOF
+`/home/oggy` is not writable.
+Bundler will use `/TMP/bundler/home/USER' as your home directory temporarily.
+EOF
+          expect(Bundler.ui).to receive(:warn).with(message)
+          expect(Bundler.user_home).to eq(Pathname("/TMP/bundler/home/USER"))
+        end
+
+        context ".bundle exists and have correct permissions" do
+          it "should return the user home" do
+            allow(Bundler.rubygems).to receive(:user_home).and_return(path)
+            allow(File).to receive(:directory?).with(path).and_return true
+            allow(File).to receive(:writable?).with(path).and_return false
+            allow(File).to receive(:directory?).with(dotbundle).and_return true
+            allow(File).to receive(:writable?).with(dotbundle).and_return true
+            expect(Bundler.user_home).to eq(Pathname(path))
+          end
+        end
+      end
+    end
+
+    context "home directory is not set" do
+      it "should issue warning and return a temporary user home" do
+        allow(Bundler.rubygems).to receive(:user_home).and_return(nil)
+        allow(Etc).to receive(:getlogin).and_return("USER")
+        allow(Dir).to receive(:tmpdir).and_return("/TMP")
+        allow(FileTest).to receive(:exist?).with("/TMP/bundler/home").and_return(true)
+        expect(FileUtils).to receive(:mkpath).with("/TMP/bundler/home/USER")
+        message = <<EOF
+Your home directory is not set.
+Bundler will use `/TMP/bundler/home/USER' as your home directory temporarily.
+EOF
+        expect(Bundler.ui).to receive(:warn).with(message)
+        expect(Bundler.user_home).to eq(Pathname("/TMP/bundler/home/USER"))
+      end
+    end
+  end
+
+  describe "#tmp_home_path" do
+    it "should create temporary user home" do
+      allow(Dir).to receive(:tmpdir).and_return("/TMP")
+      allow(FileTest).to receive(:exist?).with("/TMP/bundler/home").and_return(false)
+      expect(FileUtils).to receive(:mkpath).once.ordered.with("/TMP/bundler/home")
+      expect(FileUtils).to receive(:mkpath).once.ordered.with("/TMP/bundler/home/USER")
+      expect(File).to receive(:chmod).with(0o777, "/TMP/bundler/home")
+      expect(Bundler.tmp_home_path("USER", "")).to eq(Pathname("/TMP/bundler/home/USER"))
+    end
+  end
+
+  describe "#requires_sudo?" do
+    let!(:tmpdir) { Dir.mktmpdir }
+    let(:bundle_path) { Pathname("#{tmpdir}/bundle") }
+
+    def clear_cached_requires_sudo
+      # Private in ruby 1.8.7
+      return unless Bundler.instance_variable_defined?(:@requires_sudo_ran)
+      Bundler.send(:remove_instance_variable, :@requires_sudo_ran)
+      Bundler.send(:remove_instance_variable, :@requires_sudo)
+    end
+
+    before do
+      clear_cached_requires_sudo
+      allow(Bundler).to receive(:which).with("sudo").and_return("/usr/bin/sudo")
+      allow(Bundler).to receive(:bundle_path).and_return(bundle_path)
+    end
+
+    after do
+      FileUtils.rm_rf(tmpdir)
+      clear_cached_requires_sudo
+    end
+
+    subject { Bundler.requires_sudo? }
+
+    context "bundle_path doesn't exist" do
+      it { should be false }
+
+      context "and parent dir can't be written" do
+        before do
+          FileUtils.chmod(0o500, tmpdir)
+        end
+
+        it { should be true }
+      end
+
+      context "with unwritable files in a parent dir" do
+        # Regression test for https://github.com/bundler/bundler/pull/6316
+        # It doesn't matter if there are other unwritable files so long as
+        # bundle_path can be created
+        before do
+          file = File.join(tmpdir, "unrelated_file")
+          FileUtils.touch(file)
+          FileUtils.chmod(0o400, file)
+        end
+
+        it { should be false }
+      end
+    end
+
+    context "bundle_path exists" do
+      before do
+        FileUtils.mkdir_p(bundle_path)
+      end
+
+      it { should be false }
+
+      context "and is unwritable" do
+        before do
+          FileUtils.chmod(0o500, bundle_path)
+        end
+
+        it { should be true }
+      end
+    end
+  end
+
+  describe "#requires_sudo?" do
+    before do
+      allow(Bundler).to receive(:which).with("sudo").and_return("/usr/bin/sudo")
+      FileUtils.mkdir_p("tmp/vendor/bundle")
+      FileUtils.mkdir_p("tmp/vendor/bin_dir")
+    end
+    after do
+      FileUtils.rm_rf("tmp/vendor/bundle")
+      FileUtils.rm_rf("tmp/vendor/bin_dir")
+      if Bundler.respond_to?(:remove_instance_variable)
+        Bundler.remove_instance_variable(:@requires_sudo_ran)
+        Bundler.remove_instance_variable(:@requires_sudo)
+      else
+        # TODO: Remove these code when Bundler drops Ruby 1.8.7 support
+        Bundler.send(:remove_instance_variable, :@requires_sudo_ran)
+        Bundler.send(:remove_instance_variable, :@requires_sudo)
+      end
+    end
+    context "writable paths" do
+      it "should return false and display nothing" do
+        allow(Bundler).to receive(:bundle_path).and_return(Pathname("tmp/vendor/bundle"))
+        expect(Bundler.ui).to_not receive(:warn)
+        expect(Bundler.requires_sudo?).to eq(false)
+      end
+    end
+    context "unwritable paths" do
+      before do
+        FileUtils.touch("tmp/vendor/bundle/unwritable1.txt")
+        FileUtils.touch("tmp/vendor/bundle/unwritable2.txt")
+        FileUtils.touch("tmp/vendor/bin_dir/unwritable3.txt")
+        FileUtils.chmod(0o400, "tmp/vendor/bundle/unwritable1.txt")
+        FileUtils.chmod(0o400, "tmp/vendor/bundle/unwritable2.txt")
+        FileUtils.chmod(0o400, "tmp/vendor/bin_dir/unwritable3.txt")
+      end
+      it "should return true and display warn message" do
+        allow(Bundler).to receive(:bundle_path).and_return(Pathname("tmp/vendor/bundle"))
+        bin_dir = Pathname("tmp/vendor/bin_dir/")
+
+        # allow File#writable? to be called with args other than the stubbed on below
+        allow(File).to receive(:writable?).and_call_original
+
+        # fake make the directory unwritable
+        allow(File).to receive(:writable?).with(bin_dir).and_return(false)
+        allow(Bundler).to receive(:system_bindir).and_return(Pathname("tmp/vendor/bin_dir/"))
+        message = <<-MESSAGE.chomp
+Following files may not be writable, so sudo is needed:
+  tmp/vendor/bin_dir/
+  tmp/vendor/bundle/unwritable1.txt
+  tmp/vendor/bundle/unwritable2.txt
+MESSAGE
+        expect(Bundler.ui).to receive(:warn).with(message)
+        expect(Bundler.requires_sudo?).to eq(true)
+      end
+    end
+  end
+
+  context "user cache dir" do
+    let(:home_path)                  { Pathname.new(ENV["HOME"]) }
+
+    let(:xdg_data_home)              { home_path.join(".local") }
+    let(:xdg_cache_home)             { home_path.join(".cache") }
+    let(:xdg_config_home)            { home_path.join(".config") }
+
+    let(:bundle_user_home_default)   { home_path.join(".bundle") }
+    let(:bundle_user_home_custom)    { xdg_data_home.join("bundle") }
+
+    let(:bundle_user_cache_default)  { bundle_user_home_default.join("cache") }
+    let(:bundle_user_cache_custom)   { xdg_cache_home.join("bundle") }
+
+    let(:bundle_user_config_default) { bundle_user_home_default.join("config") }
+    let(:bundle_user_config_custom)  { xdg_config_home.join("bundle") }
+
+    let(:bundle_user_plugin_default) { bundle_user_home_default.join("plugin") }
+    let(:bundle_user_plugin_custom)  { xdg_data_home.join("bundle").join("plugin") }
+
+    describe "#user_bundle_path" do
+      before do
+        allow(Bundler.rubygems).to receive(:user_home).and_return(home_path)
+      end
+
+      it "should use the default home path" do
+        expect(Bundler.user_bundle_path).to           eq(bundle_user_home_default)
+        expect(Bundler.user_bundle_path("home")).to   eq(bundle_user_home_default)
+        expect(Bundler.user_bundle_path("cache")).to  eq(bundle_user_cache_default)
+        expect(Bundler.user_cache).to                 eq(bundle_user_cache_default)
+        expect(Bundler.user_bundle_path("config")).to eq(bundle_user_config_default)
+        expect(Bundler.user_bundle_path("plugin")).to eq(bundle_user_plugin_default)
+      end
+
+      it "should use custom home path as root for other paths" do
+        ENV["BUNDLE_USER_HOME"] = bundle_user_home_custom.to_s
+        expect(Bundler.user_bundle_path).to           eq(bundle_user_home_custom)
+        expect(Bundler.user_bundle_path("home")).to   eq(bundle_user_home_custom)
+        expect(Bundler.user_bundle_path("cache")).to  eq(bundle_user_home_custom.join("cache"))
+        expect(Bundler.user_cache).to                 eq(bundle_user_home_custom.join("cache"))
+        expect(Bundler.user_bundle_path("config")).to eq(bundle_user_home_custom.join("config"))
+        expect(Bundler.user_bundle_path("plugin")).to eq(bundle_user_home_custom.join("plugin"))
+      end
+
+      it "should use all custom paths, except home" do
+        ENV.delete("BUNDLE_USER_HOME")
+        ENV["BUNDLE_USER_CACHE"]  = bundle_user_cache_custom.to_s
+        ENV["BUNDLE_USER_CONFIG"] = bundle_user_config_custom.to_s
+        ENV["BUNDLE_USER_PLUGIN"] = bundle_user_plugin_custom.to_s
+        expect(Bundler.user_bundle_path).to           eq(bundle_user_home_default)
+        expect(Bundler.user_bundle_path("home")).to   eq(bundle_user_home_default)
+        expect(Bundler.user_bundle_path("cache")).to  eq(bundle_user_cache_custom)
+        expect(Bundler.user_cache).to                 eq(bundle_user_cache_custom)
+        expect(Bundler.user_bundle_path("config")).to eq(bundle_user_config_custom)
+        expect(Bundler.user_bundle_path("plugin")).to eq(bundle_user_plugin_custom)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/cli_spec.rb b/spec/bundler/bundler/cli_spec.rb
new file mode 100644
index 0000000000..c82d46587e
--- /dev/null
+++ b/spec/bundler/bundler/cli_spec.rb
@@ -0,0 +1,173 @@
+# frozen_string_literal: true
+
+require "bundler/cli"
+
+RSpec.describe "bundle executable" do
+  it "returns non-zero exit status when passed unrecognized options" do
+    bundle "--invalid_argument"
+    expect(exitstatus).to_not be_zero if exitstatus
+  end
+
+  it "returns non-zero exit status when passed unrecognized task" do
+    bundle "unrecognized-task"
+    expect(exitstatus).to_not be_zero if exitstatus
+  end
+
+  it "looks for a binary and executes it if it's named bundler-<task>" do
+    File.open(tmp("bundler-testtasks"), "w", 0o755) do |f|
+      ruby = ENV["BUNDLE_RUBY"] || "/usr/bin/env ruby"
+      f.puts "#!#{ruby}\nputs 'Hello, world'\n"
+    end
+
+    with_path_added(tmp) do
+      bundle "testtasks"
+    end
+
+    expect(exitstatus).to be_zero if exitstatus
+    expect(out).to eq("Hello, world")
+  end
+
+  context "with no arguments" do
+    it "prints a concise help message", :bundler => "2" do
+      bundle! ""
+      expect(last_command.stderr).to be_empty
+      expect(last_command.stdout).to include("Bundler version #{Bundler::VERSION}").
+        and include("\n\nBundler commands:\n\n").
+        and include("\n\n  Primary commands:\n").
+        and include("\n\n  Utilities:\n").
+        and include("\n\nOptions:\n")
+    end
+  end
+
+  context "when ENV['BUNDLE_GEMFILE'] is set to an empty string" do
+    it "ignores it" do
+      gemfile bundled_app("Gemfile"), <<-G
+        source "file://#{gem_repo1}"
+        gem 'rack'
+      G
+
+      bundle :install, :env => { "BUNDLE_GEMFILE" => "" }
+
+      expect(the_bundle).to include_gems "rack 1.0.0"
+    end
+  end
+
+  context "when ENV['RUBYGEMS_GEMDEPS'] is set" do
+    it "displays a warning" do
+      gemfile bundled_app("Gemfile"), <<-G
+        source "file://#{gem_repo1}"
+        gem 'rack'
+      G
+
+      bundle :install, :env => { "RUBYGEMS_GEMDEPS" => "foo" }
+      expect(out).to include("RUBYGEMS_GEMDEPS")
+      expect(out).to include("conflict with Bundler")
+
+      bundle :install, :env => { "RUBYGEMS_GEMDEPS" => "" }
+      expect(out).not_to include("RUBYGEMS_GEMDEPS")
+    end
+  end
+
+  context "with --verbose" do
+    it "prints the running command" do
+      gemfile ""
+      bundle! "info bundler", :verbose => true
+      expect(last_command.stdout).to start_with("Running `bundle info bundler --verbose` with bundler #{Bundler::VERSION}")
+    end
+
+    it "doesn't print defaults" do
+      install_gemfile! "", :verbose => true
+      expect(last_command.stdout).to start_with("Running `bundle install --retry 0 --verbose` with bundler #{Bundler::VERSION}")
+    end
+
+    it "doesn't print defaults" do
+      install_gemfile! "", :verbose => true
+      expect(last_command.stdout).to start_with("Running `bundle install --retry 0 --verbose` with bundler #{Bundler::VERSION}")
+    end
+  end
+
+  describe "printing the outdated warning" do
+    shared_examples_for "no warning" do
+      it "prints no warning" do
+        bundle "fail"
+        expect(last_command.stdboth).to eq("Could not find command \"fail\".")
+      end
+    end
+
+    let(:bundler_version) { "1.1" }
+    let(:latest_version) { nil }
+    before do
+      bundle! "config --global disable_version_check false"
+
+      simulate_bundler_version(bundler_version)
+      if latest_version
+        info_path = home(".bundle/cache/compact_index/rubygems.org.443.29b0360b937aa4d161703e6160654e47/info/bundler")
+        info_path.parent.mkpath
+        info_path.open("w") {|f| f.write "#{latest_version}\n" }
+      end
+    end
+
+    context "when there is no latest version" do
+      include_examples "no warning"
+    end
+
+    context "when the latest version is equal to the current version" do
+      let(:latest_version) { bundler_version }
+      include_examples "no warning"
+    end
+
+    context "when the latest version is less than the current version" do
+      let(:latest_version) { "0.9" }
+      include_examples "no warning"
+    end
+
+    context "when the latest version is greater than the current version" do
+      let(:latest_version) { "222.0" }
+      it "prints the version warning" do
+        bundle "fail"
+        expect(last_command.stdout).to start_with(<<-EOS.strip)
+The latest bundler is #{latest_version}, but you are currently running #{bundler_version}.
+To install the latest version, run `gem install bundler`
+        EOS
+      end
+
+      context "and disable_version_check is set" do
+        before { bundle! "config disable_version_check true" }
+        include_examples "no warning"
+      end
+
+      context "running a parseable command" do
+        it "prints no warning" do
+          bundle! "config --parseable foo"
+          expect(last_command.stdboth).to eq ""
+
+          bundle "platform --ruby"
+          expect(last_command.stdboth).to eq "Could not locate Gemfile"
+        end
+      end
+
+      context "and is a pre-release" do
+        let(:latest_version) { "222.0.0.pre.4" }
+        it "prints the version warning" do
+          bundle "fail"
+          expect(last_command.stdout).to start_with(<<-EOS.strip)
+The latest bundler is #{latest_version}, but you are currently running #{bundler_version}.
+To install the latest version, run `gem install bundler --pre`
+          EOS
+        end
+      end
+    end
+  end
+end
+
+RSpec.describe "bundler executable" do
+  it "shows the bundler version just as the `bundle` executable does", :bundler => "< 2" do
+    bundler "--version"
+    expect(out).to eq("Bundler version #{Bundler::VERSION}")
+  end
+
+  it "shows the bundler version just as the `bundle` executable does", :bundler => "2" do
+    bundler "--version"
+    expect(out).to eq(Bundler::VERSION)
+  end
+end
diff --git a/spec/bundler/bundler/compact_index_client/updater_spec.rb b/spec/bundler/bundler/compact_index_client/updater_spec.rb
new file mode 100644
index 0000000000..fd554a7b0d
--- /dev/null
+++ b/spec/bundler/bundler/compact_index_client/updater_spec.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require "net/http"
+require "bundler/compact_index_client"
+require "bundler/compact_index_client/updater"
+
+RSpec.describe Bundler::CompactIndexClient::Updater do
+  let(:fetcher) { double(:fetcher) }
+  let(:local_path) { Pathname("/tmp/localpath") }
+  let(:remote_path) { double(:remote_path) }
+
+  subject(:updater) { described_class.new(fetcher) }
+
+  context "when the ETag header is missing" do
+    # Regression test for https://github.com/bundler/bundler/issues/5463
+
+    let(:response) { double(:response, :body => "") }
+
+    it "MisMatchedChecksumError is raised" do
+      # Twice: #update retries on failure
+      expect(response).to receive(:[]).with("Content-Encoding").twice { "" }
+      expect(response).to receive(:[]).with("ETag").twice { nil }
+      expect(fetcher).to receive(:call).twice { response }
+
+      expect do
+        updater.update(local_path, remote_path)
+      end.to raise_error(Bundler::CompactIndexClient::Updater::MisMatchedChecksumError)
+    end
+  end
+
+  context "when the download is corrupt" do
+    let(:response) { double(:response, :body => "") }
+
+    it "raises HTTPError" do
+      expect(response).to receive(:[]).with("Content-Encoding") { "gzip" }
+      expect(fetcher).to receive(:call) { response }
+
+      expect do
+        updater.update(local_path, remote_path)
+      end.to raise_error(Bundler::HTTPError)
+    end
+  end
+
+  context "when bundler doesn't have permissions on Dir.tmpdir" do
+    let(:response) { double(:response, :body => "") }
+
+    it "Errno::EACCES is raised" do
+      allow(Dir).to receive(:mktmpdir) { raise Errno::EACCES }
+
+      expect do
+        updater.update(local_path, remote_path)
+      end.to raise_error(Bundler::PermissionError)
+    end
+  end
+end
diff --git a/spec/bundler/bundler/definition_spec.rb b/spec/bundler/bundler/definition_spec.rb
new file mode 100644
index 0000000000..2ed87ec81d
--- /dev/null
+++ b/spec/bundler/bundler/definition_spec.rb
@@ -0,0 +1,358 @@
+# frozen_string_literal: true
+
+require "bundler/definition"
+
+RSpec.describe Bundler::Definition do
+  describe "#lock" do
+    before do
+      allow(Bundler).to receive(:settings) { Bundler::Settings.new(".") }
+      allow(Bundler::SharedHelpers).to receive(:find_gemfile) { Pathname.new("Gemfile") }
+      allow(Bundler).to receive(:ui) { double("UI", :info => "", :debug => "") }
+    end
+    context "when it's not possible to write to the file" do
+      subject { Bundler::Definition.new(nil, [], Bundler::SourceList.new, []) }
+
+      it "raises an PermissionError with explanation" do
+        expect(File).to receive(:open).with("Gemfile.lock", "wb").
+          and_raise(Errno::EACCES)
+        expect { subject.lock("Gemfile.lock") }.
+          to raise_error(Bundler::PermissionError, /Gemfile\.lock/)
+      end
+    end
+    context "when a temporary resource access issue occurs" do
+      subject { Bundler::Definition.new(nil, [], Bundler::SourceList.new, []) }
+
+      it "raises a TemporaryResourceError with explanation" do
+        expect(File).to receive(:open).with("Gemfile.lock", "wb").
+          and_raise(Errno::EAGAIN)
+        expect { subject.lock("Gemfile.lock") }.
+          to raise_error(Bundler::TemporaryResourceError, /temporarily unavailable/)
+      end
+    end
+  end
+
+  describe "detects changes" do
+    it "for a path gem with changes", :bundler => "< 2" do
+      build_lib "foo", "1.0", :path => lib_path("foo")
+
+      install_gemfile <<-G
+        source "file://localhost#{gem_repo1}"
+        gem "foo", :path => "#{lib_path("foo")}"
+      G
+
+      build_lib "foo", "1.0", :path => lib_path("foo") do |s|
+        s.add_dependency "rack", "1.0"
+      end
+
+      bundle :install, :env => { "DEBUG" => 1 }
+
+      expect(out).to match(/re-resolving dependencies/)
+      lockfile_should_be <<-G
+        PATH
+          remote: #{lib_path("foo")}
+          specs:
+            foo (1.0)
+              rack (= 1.0)
+
+        GEM
+          remote: file://localhost#{gem_repo1}/
+          specs:
+            rack (1.0.0)
+
+        PLATFORMS
+          ruby
+
+        DEPENDENCIES
+          foo!
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      G
+    end
+
+    it "for a path gem with changes", :bundler => "2" do
+      build_lib "foo", "1.0", :path => lib_path("foo")
+
+      install_gemfile <<-G
+        source "file://localhost#{gem_repo1}"
+        gem "foo", :path => "#{lib_path("foo")}"
+      G
+
+      build_lib "foo", "1.0", :path => lib_path("foo") do |s|
+        s.add_dependency "rack", "1.0"
+      end
+
+      bundle :install, :env => { "DEBUG" => 1 }
+
+      expect(out).to match(/re-resolving dependencies/)
+      lockfile_should_be <<-G
+        GEM
+          remote: file://localhost#{gem_repo1}/
+          specs:
+            rack (1.0.0)
+
+        PATH
+          remote: #{lib_path("foo")}
+          specs:
+            foo (1.0)
+              rack (= 1.0)
+
+        PLATFORMS
+          #{lockfile_platforms}
+
+        DEPENDENCIES
+          foo!
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      G
+    end
+
+    it "for a path gem with deps and no changes", :bundler => "< 2" do
+      build_lib "foo", "1.0", :path => lib_path("foo") do |s|
+        s.add_dependency "rack", "1.0"
+        s.add_development_dependency "net-ssh", "1.0"
+      end
+
+      install_gemfile <<-G
+        source "file://localhost#{gem_repo1}"
+        gem "foo", :path => "#{lib_path("foo")}"
+      G
+
+      bundle :check, :env => { "DEBUG" => 1 }
+
+      expect(out).to match(/using resolution from the lockfile/)
+      lockfile_should_be <<-G
+        PATH
+          remote: #{lib_path("foo")}
+          specs:
+            foo (1.0)
+              rack (= 1.0)
+
+        GEM
+          remote: file://localhost#{gem_repo1}/
+          specs:
+            rack (1.0.0)
+
+        PLATFORMS
+          ruby
+
+        DEPENDENCIES
+          foo!
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      G
+    end
+
+    it "for a path gem with deps and no changes", :bundler => "2" do
+      build_lib "foo", "1.0", :path => lib_path("foo") do |s|
+        s.add_dependency "rack", "1.0"
+        s.add_development_dependency "net-ssh", "1.0"
+      end
+
+      install_gemfile <<-G
+        source "file://localhost#{gem_repo1}"
+        gem "foo", :path => "#{lib_path("foo")}"
+      G
+
+      bundle :check, :env => { "DEBUG" => 1 }
+
+      expect(out).to match(/using resolution from the lockfile/)
+      lockfile_should_be <<-G
+        GEM
+          remote: file://localhost#{gem_repo1}/
+          specs:
+            rack (1.0.0)
+
+        PATH
+          remote: #{lib_path("foo")}
+          specs:
+            foo (1.0)
+              rack (= 1.0)
+
+        PLATFORMS
+          #{lockfile_platforms}
+
+        DEPENDENCIES
+          foo!
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      G
+    end
+
+    it "for a rubygems gem" do
+      install_gemfile <<-G
+        source "file://localhost#{gem_repo1}"
+        gem "foo"
+      G
+
+      bundle :check, :env => { "DEBUG" => 1 }
+
+      expect(out).to match(/using resolution from the lockfile/)
+      lockfile_should_be <<-G
+        GEM
+          remote: file://localhost#{gem_repo1}/
+          specs:
+            foo (1.0)
+
+        PLATFORMS
+          #{lockfile_platforms}
+
+        DEPENDENCIES
+          foo
+
+        BUNDLED WITH
+           #{Bundler::VERSION}
+      G
+    end
+  end
+
+  describe "initialize" do
+    context "gem version promoter" do
+      context "with lockfile" do
+        before do
+          install_gemfile <<-G
+          source "file://#{gem_repo1}"
+          gem "foo"
+          G
+        end
+
+        it "should get a locked specs list when updating all" do
+          definition = Bundler::Definition.new(bundled_app("Gemfile.lock"), [], Bundler::SourceList.new, true)
+          locked_specs = definition.gem_version_promoter.locked_specs
+          expect(locked_specs.to_a.map(&:name)).to eq ["foo"]
+          expect(definition.instance_variable_get("@locked_specs").empty?).to eq true
+        end
+      end
+
+      context "without gemfile or lockfile" do
+        it "should not attempt to parse empty lockfile contents" do
+          definition = Bundler::Definition.new(nil, [], mock_source_list, true)
+          expect(definition.gem_version_promoter.locked_specs.to_a).to eq []
+        end
+      end
+
+      context "eager unlock" do
+        let(:source_list) do
+          Bundler::SourceList.new.tap do |source_list|
+            source_list.global_rubygems_source = "file://#{gem_repo4}"
+          end
+        end
+
+        before do
+          gemfile <<-G
+            source "file://#{gem_repo4}"
+            gem 'isolated_owner'
+
+            gem 'shared_owner_a'
+            gem 'shared_owner_b'
+          G
+
+          lockfile <<-L
+            GEM
+              remote: file://#{gem_repo4}
+              specs:
+                isolated_dep (2.0.1)
+                isolated_owner (1.0.1)
+                  isolated_dep (~> 2.0)
+                shared_dep (5.0.1)
+                shared_owner_a (3.0.1)
+                  shared_dep (~> 5.0)
+                shared_owner_b (4.0.1)
+                  shared_dep (~> 5.0)
+
+            PLATFORMS
+              ruby
+
+            DEPENDENCIES
+              shared_owner_a
+              shared_owner_b
+              isolated_owner
+
+            BUNDLED WITH
+               1.13.0
+          L
+        end
+
+        it "should not eagerly unlock shared dependency with bundle install conservative updating behavior" do
+          updated_deps_in_gemfile = [Bundler::Dependency.new("isolated_owner", ">= 0"),
+                                     Bundler::Dependency.new("shared_owner_a", "3.0.2"),
+                                     Bundler::Dependency.new("shared_owner_b", ">= 0")]
+          unlock_hash_for_bundle_install = {}
+          definition = Bundler::Definition.new(
+            bundled_app("Gemfile.lock"),
+            updated_deps_in_gemfile,
+            source_list,
+            unlock_hash_for_bundle_install
+          )
+          locked = definition.send(:converge_locked_specs).map(&:name)
+          expect(locked).to include "shared_dep"
+        end
+
+        it "should not eagerly unlock shared dependency with bundle update conservative updating behavior" do
+          updated_deps_in_gemfile = [Bundler::Dependency.new("isolated_owner", ">= 0"),
+                                     Bundler::Dependency.new("shared_owner_a", ">= 0"),
+                                     Bundler::Dependency.new("shared_owner_b", ">= 0")]
+          definition = Bundler::Definition.new(
+            bundled_app("Gemfile.lock"),
+            updated_deps_in_gemfile,
+            source_list,
+            :gems => ["shared_owner_a"], :lock_shared_dependencies => true
+          )
+          locked = definition.send(:converge_locked_specs).map(&:name)
+          expect(locked).to eq %w[isolated_dep isolated_owner shared_dep shared_owner_b]
+          expect(locked.include?("shared_dep")).to be_truthy
+        end
+      end
+    end
+  end
+
+  describe "find_resolved_spec" do
+    it "with no platform set in SpecSet" do
+      ss = Bundler::SpecSet.new([build_stub_spec("a", "1.0"), build_stub_spec("b", "1.0")])
+      dfn = Bundler::Definition.new(nil, [], mock_source_list, true)
+      dfn.instance_variable_set("@specs", ss)
+      found = dfn.find_resolved_spec(build_spec("a", "0.9", "ruby").first)
+      expect(found.name).to eq "a"
+      expect(found.version.to_s).to eq "1.0"
+    end
+  end
+
+  describe "find_indexed_specs" do
+    it "with no platform set in indexed specs" do
+      index = Bundler::Index.new
+      %w[1.0.0 1.0.1 1.1.0].each {|v| index << build_stub_spec("foo", v) }
+
+      dfn = Bundler::Definition.new(nil, [], mock_source_list, true)
+      dfn.instance_variable_set("@index", index)
+      found = dfn.find_indexed_specs(build_spec("foo", "0.9", "ruby").first)
+      expect(found.length).to eq 3
+    end
+  end
+
+  def build_stub_spec(name, version)
+    Bundler::StubSpecification.new(name, version, nil, nil)
+  end
+
+  def mock_source_list
+    Class.new do
+      def all_sources
+        []
+      end
+
+      def path_sources
+        []
+      end
+
+      def rubygems_remotes
+        []
+      end
+
+      def replace_sources!(arg)
+        nil
+      end
+    end.new
+  end
+end
diff --git a/spec/bundler/bundler/dep_proxy_spec.rb b/spec/bundler/bundler/dep_proxy_spec.rb
new file mode 100644
index 0000000000..0f8d6b1076
--- /dev/null
+++ b/spec/bundler/bundler/dep_proxy_spec.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::DepProxy do
+  let(:dep) { Bundler::Dependency.new("rake", ">= 0") }
+  subject { described_class.new(dep, Gem::Platform::RUBY) }
+  let(:same) { subject }
+  let(:other) { subject.dup }
+  let(:different) { described_class.new(dep, Gem::Platform::JAVA) }
+
+  describe "#eql?" do
+    it { expect(subject.eql?(same)).to be true }
+    it { expect(subject.eql?(other)).to be true }
+    it { expect(subject.eql?(different)).to be false }
+    it { expect(subject.eql?(nil)).to be false }
+    it { expect(subject.eql?("foobar")).to be false }
+  end
+
+  describe "#hash" do
+    it { expect(subject.hash).to eq(same.hash) }
+    it { expect(subject.hash).to eq(other.hash) }
+  end
+end
diff --git a/spec/bundler/bundler/dsl_spec.rb b/spec/bundler/bundler/dsl_spec.rb
new file mode 100644
index 0000000000..bffe4f1608
--- /dev/null
+++ b/spec/bundler/bundler/dsl_spec.rb
@@ -0,0 +1,289 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Dsl do
+  before do
+    @rubygems = double("rubygems")
+    allow(Bundler::Source::Rubygems).to receive(:new) { @rubygems }
+  end
+
+  describe "#git_source" do
+    it "registers custom hosts" do
+      subject.git_source(:example) {|repo_name| "git@git.example.com:#{repo_name}.git" }
+      subject.git_source(:foobar) {|repo_name| "git@foobar.com:#{repo_name}.git" }
+      subject.gem("dobry-pies", :example => "strzalek/dobry-pies")
+      example_uri = "git@git.example.com:strzalek/dobry-pies.git"
+      expect(subject.dependencies.first.source.uri).to eq(example_uri)
+    end
+
+    it "raises exception on invalid hostname" do
+      expect do
+        subject.git_source(:group) {|repo_name| "git@git.example.com:#{repo_name}.git" }
+      end.to raise_error(Bundler::InvalidOption)
+    end
+
+    it "expects block passed" do
+      expect { subject.git_source(:example) }.to raise_error(Bundler::InvalidOption)
+    end
+
+    context "default hosts (git, gist)", :bundler => "< 2" do
+      it "converts :github to :git" do
+        subject.gem("sparks", :github => "indirect/sparks")
+        github_uri = "git://github.com/indirect/sparks.git"
+        expect(subject.dependencies.first.source.uri).to eq(github_uri)
+      end
+
+      it "converts numeric :gist to :git" do
+        subject.gem("not-really-a-gem", :gist => 2_859_988)
+        github_uri = "https://gist.github.com/2859988.git"
+        expect(subject.dependencies.first.source.uri).to eq(github_uri)
+      end
+
+      it "converts :gist to :git" do
+        subject.gem("not-really-a-gem", :gist => "2859988")
+        github_uri = "https://gist.github.com/2859988.git"
+        expect(subject.dependencies.first.source.uri).to eq(github_uri)
+      end
+
+      it "converts 'rails' to 'rails/rails'" do
+        subject.gem("rails", :github => "rails")
+        github_uri = "git://github.com/rails/rails.git"
+        expect(subject.dependencies.first.source.uri).to eq(github_uri)
+      end
+
+      it "converts :bitbucket to :git" do
+        subject.gem("not-really-a-gem", :bitbucket => "mcorp/flatlab-rails")
+        bitbucket_uri = "https://mcorp@bitbucket.org/mcorp/flatlab-rails.git"
+        expect(subject.dependencies.first.source.uri).to eq(bitbucket_uri)
+      end
+
+      it "converts 'mcorp' to 'mcorp/mcorp'" do
+        subject.gem("not-really-a-gem", :bitbucket => "mcorp")
+        bitbucket_uri = "https://mcorp@bitbucket.org/mcorp/mcorp.git"
+        expect(subject.dependencies.first.source.uri).to eq(bitbucket_uri)
+      end
+    end
+
+    context "default git sources", :bundler => "2" do
+      it "has none" do
+        expect(subject.instance_variable_get(:@git_sources)).to eq({})
+      end
+    end
+  end
+
+  describe "#method_missing" do
+    it "raises an error for unknown DSL methods" do
+      expect(Bundler).to receive(:read_file).with(bundled_app("Gemfile").to_s).
+        and_return("unknown")
+
+      error_msg = "There was an error parsing `Gemfile`: Undefined local variable or method `unknown' for Gemfile. Bundler cannot continue."
+      expect { subject.eval_gemfile("Gemfile") }.
+        to raise_error(Bundler::GemfileError, Regexp.new(error_msg))
+    end
+  end
+
+  describe "#eval_gemfile" do
+    it "handles syntax errors with a useful message" do
+      expect(Bundler).to receive(:read_file).with(bundled_app("Gemfile").to_s).and_return("}")
+      expect { subject.eval_gemfile("Gemfile") }.
+        to raise_error(Bundler::GemfileError, /There was an error parsing `Gemfile`: (syntax error, unexpected tSTRING_DEND|(compile error - )?syntax error, unexpected '\}'). Bundler cannot continue./)
+    end
+
+    it "distinguishes syntax errors from evaluation errors" do
+      expect(Bundler).to receive(:read_file).with(bundled_app("Gemfile").to_s).and_return(
+        "ruby '2.1.5', :engine => 'ruby', :engine_version => '1.2.4'"
+      )
+      expect { subject.eval_gemfile("Gemfile") }.
+        to raise_error(Bundler::GemfileError, /There was an error evaluating `Gemfile`: ruby_version must match the :engine_version for MRI/)
+    end
+  end
+
+  describe "#gem" do
+    [:ruby, :ruby_18, :ruby_19, :ruby_20, :ruby_21, :ruby_22, :ruby_23, :ruby_24, :ruby_25, :mri, :mri_18, :mri_19,
+     :mri_20, :mri_21, :mri_22, :mri_23, :mri_24, :mri_25, :jruby, :rbx, :truffleruby].each do |platform|
+      it "allows #{platform} as a valid platform" do
+        subject.gem("foo", :platform => platform)
+      end
+    end
+
+    it "rejects invalid platforms" do
+      expect { subject.gem("foo", :platform => :bogus) }.
+        to raise_error(Bundler::GemfileError, /is not a valid platform/)
+    end
+
+    it "rejects empty gem name" do
+      expect { subject.gem("") }.
+        to raise_error(Bundler::GemfileError, /an empty gem name is not valid/)
+    end
+
+    it "rejects with a leading space in the name" do
+      expect { subject.gem(" foo") }.
+        to raise_error(Bundler::GemfileError, /' foo' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects with a trailing space in the name" do
+      expect { subject.gem("foo ") }.
+        to raise_error(Bundler::GemfileError, /'foo ' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects with a space in the gem name" do
+      expect { subject.gem("fo o") }.
+        to raise_error(Bundler::GemfileError, /'fo o' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects with a tab in the gem name" do
+      expect { subject.gem("fo\to") }.
+        to raise_error(Bundler::GemfileError, /'fo\to' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects with a newline in the gem name" do
+      expect { subject.gem("fo\no") }.
+        to raise_error(Bundler::GemfileError, /'fo\no' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects with a carriage return in the gem name" do
+      expect { subject.gem("fo\ro") }.
+        to raise_error(Bundler::GemfileError, /'fo\ro' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects with a form feed in the gem name" do
+      expect { subject.gem("fo\fo") }.
+        to raise_error(Bundler::GemfileError, /'fo\fo' is not a valid gem name because it contains whitespace/)
+    end
+
+    it "rejects symbols as gem name" do
+      expect { subject.gem(:foo) }.
+        to raise_error(Bundler::GemfileError, /You need to specify gem names as Strings. Use 'gem "foo"' instead/)
+    end
+
+    it "rejects branch option on non-git gems" do
+      expect { subject.gem("foo", :branch => "test") }.
+        to raise_error(Bundler::GemfileError, /The `branch` option for `gem 'foo'` is not allowed. Only gems with a git source can specify a branch/)
+    end
+
+    it "allows specifying a branch on git gems" do
+      subject.gem("foo", :branch => "test", :git => "http://mytestrepo")
+      dep = subject.dependencies.last
+      expect(dep.name).to eq "foo"
+    end
+
+    it "allows specifying a branch on git gems with a git_source" do
+      subject.git_source(:test_source) {|n| "https://github.com/#{n}" }
+      subject.gem("foo", :branch => "test", :test_source => "bundler/bundler")
+      dep = subject.dependencies.last
+      expect(dep.name).to eq "foo"
+    end
+  end
+
+  describe "#gemspec" do
+    let(:spec) do
+      Gem::Specification.new do |gem|
+        gem.name = "example"
+        gem.platform = platform
+      end
+    end
+
+    before do
+      allow(Dir).to receive(:[]).and_return(["spec_path"])
+      allow(Bundler).to receive(:load_gemspec).with("spec_path").and_return(spec)
+      allow(Bundler).to receive(:default_gemfile).and_return(Pathname.new("./Gemfile"))
+    end
+
+    context "with a ruby platform" do
+      let(:platform) { "ruby" }
+
+      it "keeps track of the ruby platforms in the dependency" do
+        subject.gemspec
+        expect(subject.dependencies.last.platforms).to eq(Bundler::Dependency::REVERSE_PLATFORM_MAP[Gem::Platform::RUBY])
+      end
+    end
+
+    context "with a jruby platform" do
+      let(:platform) { "java" }
+
+      it "keeps track of the jruby platforms in the dependency" do
+        allow(Gem::Platform).to receive(:local).and_return(java)
+        subject.gemspec
+        expect(subject.dependencies.last.platforms).to eq(Bundler::Dependency::REVERSE_PLATFORM_MAP[Gem::Platform::JAVA])
+      end
+    end
+  end
+
+  context "can bundle groups of gems with" do
+    # git "https://github.com/rails/rails.git" do
+    #   gem "railties"
+    #   gem "action_pack"
+    #   gem "active_model"
+    # end
+    describe "#git" do
+      it "from a single repo" do
+        rails_gems = %w[railties action_pack active_model]
+        subject.git "https://github.com/rails/rails.git" do
+          rails_gems.each {|rails_gem| subject.send :gem, rails_gem }
+        end
+        expect(subject.dependencies.map(&:name)).to match_array rails_gems
+      end
+    end
+
+    # github 'spree' do
+    #   gem 'spree_core'
+    #   gem 'spree_api'
+    #   gem 'spree_backend'
+    # end
+    describe "#github", :bundler => "< 2" do
+      it "from github" do
+        spree_gems = %w[spree_core spree_api spree_backend]
+        subject.github "spree" do
+          spree_gems.each {|spree_gem| subject.send :gem, spree_gem }
+        end
+
+        subject.dependencies.each do |d|
+          expect(d.source.uri).to eq("git://github.com/spree/spree.git")
+        end
+      end
+    end
+
+    describe "#github", :bundler => "2" do
+      it "from github" do
+        expect do
+          spree_gems = %w[spree_core spree_api spree_backend]
+          subject.github "spree" do
+            spree_gems.each {|spree_gem| subject.send :gem, spree_gem }
+          end
+        end.to raise_error(Bundler::DeprecatedError, /github method has been removed/)
+      end
+    end
+  end
+
+  describe "syntax errors" do
+    it "will raise a Bundler::GemfileError" do
+      gemfile "gem 'foo', :path => /unquoted/string/syntax/error"
+      expect { Bundler::Dsl.evaluate(bundled_app("Gemfile"), nil, true) }.
+        to raise_error(Bundler::GemfileError, /There was an error parsing `Gemfile`:( compile error -)? unknown regexp options - trg. Bundler cannot continue./)
+    end
+  end
+
+  describe "Runtime errors", :unless => Bundler.current_ruby.on_18? do
+    it "will raise a Bundler::GemfileError" do
+      gemfile "s = 'foo'.freeze; s.strip!"
+      expect { Bundler::Dsl.evaluate(bundled_app("Gemfile"), nil, true) }.
+        to raise_error(Bundler::GemfileError, /There was an error parsing `Gemfile`: can't modify frozen String. Bundler cannot continue./i)
+    end
+  end
+
+  describe "#with_source" do
+    context "if there was a rubygem source already defined" do
+      it "restores it after it's done" do
+        other_source = double("other-source")
+        allow(Bundler::Source::Rubygems).to receive(:new).and_return(other_source)
+        allow(Bundler).to receive(:default_gemfile).and_return(Pathname.new("./Gemfile"))
+
+        subject.source("https://other-source.org") do
+          subject.gem("dobry-pies", :path => "foo")
+          subject.gem("foo")
+        end
+
+        expect(subject.dependencies.last.source).to eq(other_source)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/endpoint_specification_spec.rb b/spec/bundler/bundler/endpoint_specification_spec.rb
new file mode 100644
index 0000000000..a9371f6617
--- /dev/null
+++ b/spec/bundler/bundler/endpoint_specification_spec.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::EndpointSpecification do
+  let(:name)         { "foo" }
+  let(:version)      { "1.0.0" }
+  let(:platform)     { Gem::Platform::RUBY }
+  let(:dependencies) { [] }
+  let(:metadata)     { nil }
+
+  subject(:spec) { described_class.new(name, version, platform, dependencies, metadata) }
+
+  describe "#build_dependency" do
+    let(:name)           { "foo" }
+    let(:requirement1)   { "~> 1.1" }
+    let(:requirement2)   { ">= 1.1.7" }
+
+    it "should return a Gem::Dependency" do
+      expect(subject.send(:build_dependency, name, [requirement1, requirement2])).
+        to eq(Gem::Dependency.new(name, requirement1, requirement2))
+    end
+
+    context "when an ArgumentError occurs" do
+      before do
+        allow(Gem::Dependency).to receive(:new).with(name, [requirement1, requirement2]) {
+          raise ArgumentError.new("Some error occurred")
+        }
+      end
+
+      it "should raise the original error" do
+        expect { subject.send(:build_dependency, name, [requirement1, requirement2]) }.to raise_error(
+          ArgumentError, "Some error occurred"
+        )
+      end
+    end
+
+    context "when there is an ill formed requirement" do
+      before do
+        allow(Gem::Dependency).to receive(:new).with(name, [requirement1, requirement2]) {
+          raise ArgumentError.new("Ill-formed requirement [\"#<YAML::Syck::DefaultKey")
+        }
+        # Eliminate extra line break in rspec output due to `puts` in `#build_dependency`
+        allow(subject).to receive(:puts) {}
+      end
+
+      it "should raise a Bundler::GemspecError with invalid gemspec message" do
+        expect { subject.send(:build_dependency, name, [requirement1, requirement2]) }.to raise_error(
+          Bundler::GemspecError, /Unfortunately, the gem foo \(1\.0\.0\) has an invalid gemspec/
+        )
+      end
+    end
+  end
+
+  describe "#parse_metadata" do
+    context "when the metadata has malformed requirements" do
+      let(:metadata) { { "rubygems" => ">\n" } }
+      it "raises a helpful error message" do
+        expect { subject }.to raise_error(
+          Bundler::GemspecError,
+          a_string_including("There was an error parsing the metadata for the gem foo (1.0.0)").
+            and(a_string_including('The metadata was {"rubygems"=>">\n"}'))
+        )
+      end
+    end
+  end
+
+  it "supports equality comparison" do
+    other_spec = described_class.new("bar", version, platform, dependencies, metadata)
+    expect(spec).to eql(spec)
+    expect(spec).to_not eql(other_spec)
+  end
+end
diff --git a/spec/bundler/bundler/env_spec.rb b/spec/bundler/bundler/env_spec.rb
new file mode 100644
index 0000000000..20bd38b021
--- /dev/null
+++ b/spec/bundler/bundler/env_spec.rb
@@ -0,0 +1,151 @@
+# frozen_string_literal: true
+
+require "bundler/settings"
+
+RSpec.describe Bundler::Env do
+  let(:git_proxy_stub) { Bundler::Source::Git::GitProxy.new(nil, nil, nil) }
+
+  describe "#report" do
+    it "prints the environment" do
+      out = described_class.report
+
+      expect(out).to include("Environment")
+      expect(out).to include(Bundler::VERSION)
+      expect(out).to include(Gem::VERSION)
+      expect(out).to include(described_class.send(:ruby_version))
+      expect(out).to include(described_class.send(:git_version))
+      expect(out).to include(OpenSSL::OPENSSL_VERSION)
+    end
+
+    context "when there is a Gemfile and a lockfile and print_gemfile is true" do
+      before do
+        gemfile "gem 'rack', '1.0.0'"
+
+        lockfile <<-L
+          GEM
+            remote: file:#{gem_repo1}/
+            specs:
+              rack (1.0.0)
+
+          DEPENDENCIES
+            rack
+
+          BUNDLED WITH
+             1.10.0
+        L
+      end
+
+      let(:output) { described_class.report(:print_gemfile => true) }
+
+      it "prints the Gemfile" do
+        expect(output).to include("Gemfile")
+        expect(output).to include("'rack', '1.0.0'")
+      end
+
+      it "prints the lockfile" do
+        expect(output).to include("Gemfile.lock")
+        expect(output).to include("rack (1.0.0)")
+      end
+    end
+
+    context "when there no Gemfile and print_gemfile is true" do
+      let(:output) { described_class.report(:print_gemfile => true) }
+
+      it "prints the environment" do
+        expect(output).to start_with("## Environment")
+      end
+    end
+
+    context "when Gemfile contains a gemspec and print_gemspecs is true" do
+      let(:gemspec) do
+        strip_whitespace(<<-GEMSPEC)
+          Gem::Specification.new do |gem|
+            gem.name = "foo"
+            gem.author = "Fumofu"
+          end
+        GEMSPEC
+      end
+
+      before do
+        gemfile("gemspec")
+
+        File.open(bundled_app.join("foo.gemspec"), "wb") do |f|
+          f.write(gemspec)
+        end
+      end
+
+      it "prints the gemspec" do
+        output = described_class.report(:print_gemspecs => true)
+
+        expect(output).to include("foo.gemspec")
+        expect(output).to include(gemspec)
+      end
+    end
+
+    context "when eval_gemfile is used" do
+      it "prints all gemfiles" do
+        create_file "other/Gemfile-other", "gem 'rack'"
+        create_file "other/Gemfile", "eval_gemfile 'Gemfile-other'"
+        create_file "Gemfile-alt", <<-G
+          source "file:#{gem_repo1}"
+          eval_gemfile "other/Gemfile"
+        G
+        gemfile "eval_gemfile #{File.expand_path("Gemfile-alt").dump}"
+
+        output = described_class.report(:print_gemspecs => true)
+        expect(output).to include(strip_whitespace(<<-ENV))
+          ## Gemfile
+
+          ### Gemfile
+
+          ```ruby
+          eval_gemfile #{File.expand_path("Gemfile-alt").dump}
+          ```
+
+          ### Gemfile-alt
+
+          ```ruby
+          source "file:#{gem_repo1}"
+          eval_gemfile "other/Gemfile"
+          ```
+
+          ### other/Gemfile
+
+          ```ruby
+          eval_gemfile 'Gemfile-other'
+          ```
+
+          ### other/Gemfile-other
+
+          ```ruby
+          gem 'rack'
+          ```
+
+          ### Gemfile.lock
+
+          ```
+          <No #{bundled_app("Gemfile.lock")} found>
+          ```
+        ENV
+      end
+    end
+
+    context "when the git version is OS specific" do
+      it "includes OS specific information with the version number" do
+        expect(git_proxy_stub).to receive(:git).with("--version").
+          and_return("git version 1.2.3 (Apple Git-BS)")
+        expect(Bundler::Source::Git::GitProxy).to receive(:new).and_return(git_proxy_stub)
+
+        expect(described_class.report).to include("Git         1.2.3 (Apple Git-BS)")
+      end
+    end
+  end
+
+  describe ".version_of", :ruby_repo do
+    let(:parsed_version) { described_class.send(:version_of, "ruby") }
+
+    it "strips version of new line characters" do
+      expect(parsed_version).to_not include("\n")
+    end
+  end
+end
diff --git a/spec/bundler/bundler/environment_preserver_spec.rb b/spec/bundler/bundler/environment_preserver_spec.rb
new file mode 100644
index 0000000000..530ca6f835
--- /dev/null
+++ b/spec/bundler/bundler/environment_preserver_spec.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::EnvironmentPreserver do
+  let(:preserver) { described_class.new(env, ["foo"]) }
+
+  describe "#backup" do
+    let(:env) { { "foo" => "my-foo", "bar" => "my-bar" } }
+    subject { preserver.backup }
+
+    it "should create backup entries" do
+      expect(subject["BUNDLER_ORIG_foo"]).to eq("my-foo")
+    end
+
+    it "should keep the original entry" do
+      expect(subject["foo"]).to eq("my-foo")
+    end
+
+    it "should not create backup entries for unspecified keys" do
+      expect(subject.key?("BUNDLER_ORIG_bar")).to eq(false)
+    end
+
+    it "should not affect the original env" do
+      subject
+      expect(env.keys.sort).to eq(%w[bar foo])
+    end
+
+    context "when a key is empty" do
+      let(:env) { { "foo" => "" } }
+
+      it "should not create backup entries" do
+        expect(subject).not_to have_key "BUNDLER_ORIG_foo"
+      end
+    end
+
+    context "when an original key is set" do
+      let(:env) { { "foo" => "my-foo", "BUNDLER_ORIG_foo" => "orig-foo" } }
+
+      it "should keep the original value in the BUNDLER_ORIG_ variable" do
+        expect(subject["BUNDLER_ORIG_foo"]).to eq("orig-foo")
+      end
+
+      it "should keep the variable" do
+        expect(subject["foo"]).to eq("my-foo")
+      end
+    end
+  end
+
+  describe "#restore" do
+    subject { preserver.restore }
+
+    context "when an original key is set" do
+      let(:env) { { "foo" => "my-foo", "BUNDLER_ORIG_foo" => "orig-foo" } }
+
+      it "should restore the original value" do
+        expect(subject["foo"]).to eq("orig-foo")
+      end
+
+      it "should delete the backup value" do
+        expect(subject.key?("BUNDLER_ORIG_foo")).to eq(false)
+      end
+    end
+
+    context "when no original key is set" do
+      let(:env) { { "foo" => "my-foo" } }
+
+      it "should keep the current value" do
+        expect(subject["foo"]).to eq("my-foo")
+      end
+    end
+
+    context "when the original key is empty" do
+      let(:env) { { "foo" => "my-foo", "BUNDLER_ORIG_foo" => "" } }
+
+      it "should keep the current value" do
+        expect(subject["foo"]).to eq("my-foo")
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/fetcher/base_spec.rb b/spec/bundler/bundler/fetcher/base_spec.rb
new file mode 100644
index 0000000000..df1245d44d
--- /dev/null
+++ b/spec/bundler/bundler/fetcher/base_spec.rb
@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Fetcher::Base do
+  let(:downloader)  { double(:downloader) }
+  let(:remote)      { double(:remote) }
+  let(:display_uri) { "http://sample_uri.com" }
+
+  class TestClass < described_class; end
+
+  subject { TestClass.new(downloader, remote, display_uri) }
+
+  describe "#initialize" do
+    context "with the abstract Base class" do
+      it "should raise an error" do
+        expect { described_class.new(downloader, remote, display_uri) }.to raise_error(RuntimeError, "Abstract class")
+      end
+    end
+
+    context "with a class that inherits the Base class" do
+      it "should set the passed attributes" do
+        expect(subject.downloader).to eq(downloader)
+        expect(subject.remote).to eq(remote)
+        expect(subject.display_uri).to eq("http://sample_uri.com")
+      end
+    end
+  end
+
+  describe "#remote_uri" do
+    let(:remote_uri_obj) { double(:remote_uri_obj) }
+
+    before { allow(remote).to receive(:uri).and_return(remote_uri_obj) }
+
+    it "should return the remote's uri" do
+      expect(subject.remote_uri).to eq(remote_uri_obj)
+    end
+  end
+
+  describe "#fetch_uri" do
+    let(:remote_uri_obj) { URI("http://rubygems.org") }
+
+    before { allow(subject).to receive(:remote_uri).and_return(remote_uri_obj) }
+
+    context "when the remote uri's host is rubygems.org" do
+      it "should create a copy of the remote uri with index.rubygems.org as the host" do
+        fetched_uri = subject.fetch_uri
+        expect(fetched_uri.host).to eq("index.rubygems.org")
+        expect(fetched_uri).to_not be(remote_uri_obj)
+      end
+    end
+
+    context "when the remote uri's host is not rubygems.org" do
+      let(:remote_uri_obj) { URI("http://otherhost.org") }
+
+      it "should return the remote uri" do
+        expect(subject.fetch_uri).to eq(URI("http://otherhost.org"))
+      end
+    end
+
+    it "memoizes the fetched uri" do
+      expect(remote_uri_obj).to receive(:host).once
+      2.times { subject.fetch_uri }
+    end
+  end
+
+  describe "#available?" do
+    it "should return whether the api is available" do
+      expect(subject.available?).to be_truthy
+    end
+  end
+
+  describe "#api_fetcher?" do
+    it "should return false" do
+      expect(subject.api_fetcher?).to be_falsey
+    end
+  end
+end
diff --git a/spec/bundler/bundler/fetcher/compact_index_spec.rb b/spec/bundler/bundler/fetcher/compact_index_spec.rb
new file mode 100644
index 0000000000..e0f58766ea
--- /dev/null
+++ b/spec/bundler/bundler/fetcher/compact_index_spec.rb
@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Fetcher::CompactIndex do
+  let(:downloader)  { double(:downloader) }
+  let(:display_uri) { URI("http://sampleuri.com") }
+  let(:remote)      { double(:remote, :cache_slug => "lsjdf", :uri => display_uri) }
+  let(:compact_index) { described_class.new(downloader, remote, display_uri) }
+
+  before do
+    allow(compact_index).to receive(:log_specs) {}
+  end
+
+  describe "#specs_for_names" do
+    it "has only one thread open at the end of the run" do
+      compact_index.specs_for_names(["lskdjf"])
+
+      thread_count = Thread.list.count {|thread| thread.status == "run" }
+      expect(thread_count).to eq 1
+    end
+
+    it "calls worker#stop during the run" do
+      expect_any_instance_of(Bundler::Worker).to receive(:stop).at_least(:once)
+
+      compact_index.specs_for_names(["lskdjf"])
+    end
+
+    describe "#available?" do
+      before do
+        allow(compact_index).to receive(:compact_index_client).
+          and_return(double(:compact_index_client, :update_and_parse_checksums! => true))
+      end
+
+      it "returns true" do
+        expect(compact_index).to be_available
+      end
+
+      context "when OpenSSL is not available" do
+        before do
+          allow(compact_index).to receive(:require).with("openssl").and_raise(LoadError)
+        end
+
+        it "returns true" do
+          expect(compact_index).to be_available
+        end
+      end
+
+      context "when OpenSSL is FIPS-enabled", :ruby => ">= 2.0.0" do
+        def remove_cached_md5_availability
+          return unless Bundler::SharedHelpers.instance_variable_defined?(:@md5_available)
+          Bundler::SharedHelpers.remove_instance_variable(:@md5_available)
+        end
+
+        before do
+          remove_cached_md5_availability
+          stub_const("OpenSSL::OPENSSL_FIPS", true)
+        end
+
+        after { remove_cached_md5_availability }
+
+        context "when FIPS-mode is active" do
+          before do
+            allow(OpenSSL::Digest::MD5).to receive(:digest).
+              and_raise(OpenSSL::Digest::DigestError)
+          end
+
+          it "returns false" do
+            expect(compact_index).to_not be_available
+          end
+        end
+
+        it "returns true" do
+          expect(compact_index).to be_available
+        end
+      end
+    end
+
+    context "logging" do
+      before { allow(compact_index).to receive(:log_specs).and_call_original }
+
+      context "with debug on" do
+        before do
+          allow(Bundler).to receive_message_chain(:ui, :debug?).and_return(true)
+        end
+
+        it "should log at info level" do
+          expect(Bundler).to receive_message_chain(:ui, :debug).with('Looking up gems ["lskdjf"]')
+          compact_index.specs_for_names(["lskdjf"])
+        end
+      end
+
+      context "with debug off" do
+        before do
+          allow(Bundler).to receive_message_chain(:ui, :debug?).and_return(false)
+        end
+
+        it "should log at info level" do
+          expect(Bundler).to receive_message_chain(:ui, :info).with(".", false)
+          compact_index.specs_for_names(["lskdjf"])
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/fetcher/dependency_spec.rb b/spec/bundler/bundler/fetcher/dependency_spec.rb
new file mode 100644
index 0000000000..081fdff34d
--- /dev/null
+++ b/spec/bundler/bundler/fetcher/dependency_spec.rb
@@ -0,0 +1,287 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Fetcher::Dependency do
+  let(:downloader)  { double(:downloader) }
+  let(:remote)      { double(:remote, :uri => URI("http://localhost:5000")) }
+  let(:display_uri) { "http://sample_uri.com" }
+
+  subject { described_class.new(downloader, remote, display_uri) }
+
+  describe "#available?" do
+    let(:dependency_api_uri) { double(:dependency_api_uri) }
+    let(:fetched_spec)       { double(:fetched_spec) }
+
+    before do
+      allow(subject).to receive(:dependency_api_uri).and_return(dependency_api_uri)
+      allow(downloader).to receive(:fetch).with(dependency_api_uri).and_return(fetched_spec)
+    end
+
+    it "should be truthy" do
+      expect(subject.available?).to be_truthy
+    end
+
+    context "when there is no network access" do
+      before do
+        allow(downloader).to receive(:fetch).with(dependency_api_uri) {
+          raise Bundler::Fetcher::NetworkDownError.new("Network Down Message")
+        }
+      end
+
+      it "should raise an HTTPError with the original message" do
+        expect { subject.available? }.to raise_error(Bundler::HTTPError, "Network Down Message")
+      end
+    end
+
+    context "when authentication is required" do
+      let(:remote_uri) { "http://remote_uri.org" }
+
+      before do
+        allow(downloader).to receive(:fetch).with(dependency_api_uri) {
+          raise Bundler::Fetcher::AuthenticationRequiredError.new(remote_uri)
+        }
+      end
+
+      it "should raise the original error" do
+        expect { subject.available? }.to raise_error(Bundler::Fetcher::AuthenticationRequiredError,
+          %r{Authentication is required for http://remote_uri.org})
+      end
+    end
+
+    context "when there is an http error" do
+      before { allow(downloader).to receive(:fetch).with(dependency_api_uri) { raise Bundler::HTTPError.new } }
+
+      it "should be falsey" do
+        expect(subject.available?).to be_falsey
+      end
+    end
+  end
+
+  describe "#api_fetcher?" do
+    it "should return true" do
+      expect(subject.api_fetcher?).to be_truthy
+    end
+  end
+
+  describe "#specs" do
+    let(:gem_names)            { %w[foo bar] }
+    let(:full_dependency_list) { ["bar"] }
+    let(:last_spec_list)       { [["boulder", gem_version1, "ruby", resque]] }
+    let(:fail_errors)          { double(:fail_errors) }
+    let(:bundler_retry)        { double(:bundler_retry) }
+    let(:gem_version1)         { double(:gem_version1) }
+    let(:resque)               { double(:resque) }
+    let(:remote_uri)           { "http://remote-uri.org" }
+
+    before do
+      stub_const("Bundler::Fetcher::FAIL_ERRORS", fail_errors)
+      allow(Bundler::Retry).to receive(:new).with("dependency api", fail_errors).and_return(bundler_retry)
+      allow(bundler_retry).to receive(:attempts) {|&block| block.call }
+      allow(subject).to receive(:log_specs) {}
+      allow(subject).to receive(:remote_uri).and_return(remote_uri)
+      allow(Bundler).to receive_message_chain(:ui, :debug?)
+      allow(Bundler).to receive_message_chain(:ui, :info)
+      allow(Bundler).to receive_message_chain(:ui, :debug)
+    end
+
+    context "when there are given gem names that are not in the full dependency list" do
+      let(:spec_list)        { [["top", gem_version2, "ruby", faraday]] }
+      let(:deps_list)        { [] }
+      let(:dependency_specs) { [spec_list, deps_list] }
+      let(:gem_version2)     { double(:gem_version2) }
+      let(:faraday)          { double(:faraday) }
+
+      before { allow(subject).to receive(:dependency_specs).with(["foo"]).and_return(dependency_specs) }
+
+      it "should return a hash with the remote_uri and the list of specs" do
+        expect(subject.specs(gem_names, full_dependency_list, last_spec_list)).to eq([
+          ["top", gem_version2, "ruby", faraday],
+          ["boulder", gem_version1, "ruby", resque],
+        ])
+      end
+    end
+
+    context "when all given gem names are in the full dependency list" do
+      let(:gem_names)            { ["foo"] }
+      let(:full_dependency_list) { %w[foo bar] }
+      let(:last_spec_list)       { ["boulder"] }
+
+      it "should return a hash with the remote_uri and the last spec list" do
+        expect(subject.specs(gem_names, full_dependency_list, last_spec_list)).to eq(["boulder"])
+      end
+    end
+
+    context "logging" do
+      before { allow(subject).to receive(:log_specs).and_call_original }
+
+      context "with debug on" do
+        before do
+          allow(Bundler).to receive_message_chain(:ui, :debug?).and_return(true)
+          allow(subject).to receive(:dependency_specs).with(["foo"]).and_return([[], []])
+        end
+
+        it "should log the query list at debug level" do
+          expect(Bundler).to receive_message_chain(:ui, :debug).with("Query List: [\"foo\"]")
+          expect(Bundler).to receive_message_chain(:ui, :debug).with("Query List: []")
+          subject.specs(gem_names, full_dependency_list, last_spec_list)
+        end
+      end
+
+      context "with debug off" do
+        before do
+          allow(Bundler).to receive_message_chain(:ui, :debug?).and_return(false)
+          allow(subject).to receive(:dependency_specs).with(["foo"]).and_return([[], []])
+        end
+
+        it "should log at info level" do
+          expect(Bundler).to receive_message_chain(:ui, :info).with(".", false)
+          expect(Bundler).to receive_message_chain(:ui, :info).with(".", false)
+          subject.specs(gem_names, full_dependency_list, last_spec_list)
+        end
+      end
+    end
+
+    shared_examples_for "the error is properly handled" do
+      it "should return nil" do
+        expect(subject.specs(gem_names, full_dependency_list, last_spec_list)).to be_nil
+      end
+
+      context "debug logging is not on" do
+        before { allow(Bundler).to receive_message_chain(:ui, :debug?).and_return(false) }
+
+        it "should log a new line to info" do
+          expect(Bundler).to receive_message_chain(:ui, :info).with("")
+          subject.specs(gem_names, full_dependency_list, last_spec_list)
+        end
+      end
+    end
+
+    shared_examples_for "the error suggests retrying with the full index" do
+      it "should log the inability to fetch from API at debug level" do
+        expect(Bundler).to receive_message_chain(:ui, :debug).with("could not fetch from the dependency API\nit's suggested to retry using the full index via `bundle install --full-index`")
+        subject.specs(gem_names, full_dependency_list, last_spec_list)
+      end
+    end
+
+    context "when an HTTPError occurs" do
+      before { allow(subject).to receive(:dependency_specs) { raise Bundler::HTTPError.new } }
+
+      it_behaves_like "the error is properly handled"
+      it_behaves_like "the error suggests retrying with the full index"
+    end
+
+    context "when a GemspecError occurs" do
+      before { allow(subject).to receive(:dependency_specs) { raise Bundler::GemspecError.new } }
+
+      it_behaves_like "the error is properly handled"
+      it_behaves_like "the error suggests retrying with the full index"
+    end
+
+    context "when a MarshalError occurs" do
+      before { allow(subject).to receive(:dependency_specs) { raise Bundler::MarshalError.new } }
+
+      it_behaves_like "the error is properly handled"
+
+      it "should log the inability to fetch from API and mention retrying" do
+        expect(Bundler).to receive_message_chain(:ui, :debug).with("could not fetch from the dependency API, trying the full index")
+        subject.specs(gem_names, full_dependency_list, last_spec_list)
+      end
+    end
+  end
+
+  describe "#dependency_specs" do
+    let(:gem_names)                { [%w[foo bar], %w[bundler rubocop]] }
+    let(:gem_list)                 { double(:gem_list) }
+    let(:formatted_specs_and_deps) { double(:formatted_specs_and_deps) }
+
+    before do
+      allow(subject).to receive(:unmarshalled_dep_gems).with(gem_names).and_return(gem_list)
+      allow(subject).to receive(:get_formatted_specs_and_deps).with(gem_list).and_return(formatted_specs_and_deps)
+    end
+
+    it "should log the query list at debug level" do
+      expect(Bundler).to receive_message_chain(:ui, :debug).with(
+        "Query Gemcutter Dependency Endpoint API: foo,bar,bundler,rubocop"
+      )
+      subject.dependency_specs(gem_names)
+    end
+
+    it "should return formatted specs and a unique list of dependencies" do
+      expect(subject.dependency_specs(gem_names)).to eq(formatted_specs_and_deps)
+    end
+  end
+
+  describe "#unmarshalled_dep_gems" do
+    let(:gem_names)         { [%w[foo bar], %w[bundler rubocop]] }
+    let(:dep_api_uri)       { double(:dep_api_uri) }
+    let(:unmarshalled_gems) { double(:unmarshalled_gems) }
+    let(:fetch_response)    { double(:fetch_response, :body => double(:body)) }
+    let(:rubygems_limit)    { 50 }
+
+    before { allow(subject).to receive(:dependency_api_uri).with(gem_names).and_return(dep_api_uri) }
+
+    it "should fetch dependencies from RubyGems and unmarshal them" do
+      expect(gem_names).to receive(:each_slice).with(rubygems_limit).and_call_original
+      expect(downloader).to receive(:fetch).with(dep_api_uri).and_return(fetch_response)
+      expect(Bundler).to receive(:load_marshal).with(fetch_response.body).and_return([unmarshalled_gems])
+      expect(subject.unmarshalled_dep_gems(gem_names)).to eq([unmarshalled_gems])
+    end
+  end
+
+  describe "#get_formatted_specs_and_deps" do
+    let(:gem_list) do
+      [
+        {
+          :dependencies => {
+            "resque" => "req3,req4",
+          },
+          :name => "typhoeus",
+          :number => "1.0.1",
+          :platform => "ruby",
+        },
+        {
+          :dependencies => {
+            "faraday" => "req1,req2",
+          },
+          :name => "grape",
+          :number => "2.0.2",
+          :platform => "jruby",
+        },
+      ]
+    end
+
+    it "should return formatted specs and a unique list of dependencies" do
+      spec_list, deps_list = subject.get_formatted_specs_and_deps(gem_list)
+      expect(spec_list).to eq([["typhoeus", "1.0.1", "ruby", [["resque", ["req3,req4"]]]],
+                               ["grape", "2.0.2", "jruby", [["faraday", ["req1,req2"]]]]])
+      expect(deps_list).to eq(%w[resque faraday])
+    end
+  end
+
+  describe "#dependency_api_uri" do
+    let(:uri) { URI("http://gem-api.com") }
+
+    context "with gem names" do
+      let(:gem_names) { %w[foo bar bundler rubocop] }
+
+      before { allow(subject).to receive(:fetch_uri).and_return(uri) }
+
+      it "should return an api calling uri with the gems in the query" do
+        expect(subject.dependency_api_uri(gem_names).to_s).to eq(
+          "http://gem-api.com/api/v1/dependencies?gems=bar%2Cbundler%2Cfoo%2Crubocop"
+        )
+      end
+    end
+
+    context "with no gem names" do
+      let(:gem_names) { [] }
+
+      before { allow(subject).to receive(:fetch_uri).and_return(uri) }
+
+      it "should return an api calling uri with no query" do
+        expect(subject.dependency_api_uri(gem_names).to_s).to eq(
+          "http://gem-api.com/api/v1/dependencies"
+        )
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/fetcher/downloader_spec.rb b/spec/bundler/bundler/fetcher/downloader_spec.rb
new file mode 100644
index 0000000000..c9b4fa662a
--- /dev/null
+++ b/spec/bundler/bundler/fetcher/downloader_spec.rb
@@ -0,0 +1,250 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Fetcher::Downloader do
+  let(:connection)     { double(:connection) }
+  let(:redirect_limit) { 5 }
+  let(:uri)            { URI("http://www.uri-to-fetch.com/api/v2/endpoint") }
+  let(:options)        { double(:options) }
+
+  subject { described_class.new(connection, redirect_limit) }
+
+  describe "fetch" do
+    let(:counter)      { 0 }
+    let(:httpv)        { "1.1" }
+    let(:http_response) { double(:response) }
+
+    before do
+      allow(subject).to receive(:request).with(uri, options).and_return(http_response)
+      allow(http_response).to receive(:body).and_return("Body with info")
+    end
+
+    context "when the # requests counter is greater than the redirect limit" do
+      let(:counter) { redirect_limit + 1 }
+
+      it "should raise a Bundler::HTTPError specifying too many redirects" do
+        expect { subject.fetch(uri, options, counter) }.to raise_error(Bundler::HTTPError, "Too many redirects")
+      end
+    end
+
+    context "logging" do
+      let(:http_response) { Net::HTTPSuccess.new("1.1", 200, "Success") }
+
+      it "should log the HTTP response code and message to debug" do
+        expect(Bundler).to receive_message_chain(:ui, :debug).with("HTTP 200 Success #{uri}")
+        subject.fetch(uri, options, counter)
+      end
+    end
+
+    context "when the request response is a Net::HTTPRedirection" do
+      let(:http_response) { Net::HTTPRedirection.new(httpv, 308, "Moved") }
+
+      before { http_response["location"] = "http://www.redirect-uri.com/api/v2/endpoint" }
+
+      it "should try to fetch the redirect uri and iterate the # requests counter" do
+        expect(subject).to receive(:fetch).with(URI("http://www.uri-to-fetch.com/api/v2/endpoint"), options, 0).and_call_original
+        expect(subject).to receive(:fetch).with(URI("http://www.redirect-uri.com/api/v2/endpoint"), options, 1)
+        subject.fetch(uri, options, counter)
+      end
+
+      context "when the redirect uri and original uri are the same" do
+        let(:uri) { URI("ssh://username:password@www.uri-to-fetch.com/api/v2/endpoint") }
+
+        before { http_response["location"] = "ssh://www.uri-to-fetch.com/api/v1/endpoint" }
+
+        it "should set the same user and password for the redirect uri" do
+          expect(subject).to receive(:fetch).with(URI("ssh://username:password@www.uri-to-fetch.com/api/v2/endpoint"), options, 0).and_call_original
+          expect(subject).to receive(:fetch).with(URI("ssh://username:password@www.uri-to-fetch.com/api/v1/endpoint"), options, 1)
+          subject.fetch(uri, options, counter)
+        end
+      end
+    end
+
+    context "when the request response is a Net::HTTPSuccess" do
+      let(:http_response) { Net::HTTPSuccess.new("1.1", 200, "Success") }
+
+      it "should return the response body" do
+        expect(subject.fetch(uri, options, counter)).to eq(http_response)
+      end
+    end
+
+    context "when the request response is a Net::HTTPRequestEntityTooLarge" do
+      let(:http_response) { Net::HTTPRequestEntityTooLarge.new("1.1", 413, "Too Big") }
+
+      it "should raise a Bundler::Fetcher::FallbackError with the response body" do
+        expect { subject.fetch(uri, options, counter) }.to raise_error(Bundler::Fetcher::FallbackError, "Body with info")
+      end
+    end
+
+    context "when the request response is a Net::HTTPUnauthorized" do
+      let(:http_response) { Net::HTTPUnauthorized.new("1.1", 401, "Unauthorized") }
+
+      it "should raise a Bundler::Fetcher::AuthenticationRequiredError with the uri host" do
+        expect { subject.fetch(uri, options, counter) }.to raise_error(Bundler::Fetcher::AuthenticationRequiredError,
+          /Authentication is required for www.uri-to-fetch.com/)
+      end
+    end
+
+    context "when the request response is a Net::HTTPNotFound" do
+      let(:http_response) { Net::HTTPNotFound.new("1.1", 404, "Not Found") }
+
+      it "should raise a Bundler::Fetcher::FallbackError with Net::HTTPNotFound" do
+        expect { subject.fetch(uri, options, counter) }.to raise_error(Bundler::Fetcher::FallbackError, "Net::HTTPNotFound")
+      end
+    end
+
+    context "when the request response is some other type" do
+      let(:http_response) { Net::HTTPBadGateway.new("1.1", 500, "Fatal Error") }
+
+      it "should raise a Bundler::HTTPError with the response class and body" do
+        expect { subject.fetch(uri, options, counter) }.to raise_error(Bundler::HTTPError, "Net::HTTPBadGateway: Body with info")
+      end
+    end
+  end
+
+  describe "request" do
+    let(:net_http_get) { double(:net_http_get) }
+    let(:response)     { double(:response) }
+
+    before do
+      allow(Net::HTTP::Get).to receive(:new).with("/api/v2/endpoint", options).and_return(net_http_get)
+      allow(connection).to receive(:request).with(uri, net_http_get).and_return(response)
+    end
+
+    it "should log the HTTP GET request to debug" do
+      expect(Bundler).to receive_message_chain(:ui, :debug).with("HTTP GET http://www.uri-to-fetch.com/api/v2/endpoint")
+      subject.request(uri, options)
+    end
+
+    context "when there is a user provided in the request" do
+      context "and there is also a password provided" do
+        context "that contains cgi escaped characters" do
+          let(:uri) { URI("http://username:password%24@www.uri-to-fetch.com/api/v2/endpoint") }
+
+          it "should request basic authentication with the username and password" do
+            expect(net_http_get).to receive(:basic_auth).with("username", "password$")
+            subject.request(uri, options)
+          end
+        end
+
+        context "that is all unescaped characters" do
+          let(:uri) { URI("http://username:password@www.uri-to-fetch.com/api/v2/endpoint") }
+          it "should request basic authentication with the username and proper cgi compliant password" do
+            expect(net_http_get).to receive(:basic_auth).with("username", "password")
+            subject.request(uri, options)
+          end
+        end
+      end
+
+      context "and there is no password provided" do
+        let(:uri) { URI("http://username@www.uri-to-fetch.com/api/v2/endpoint") }
+
+        it "should request basic authentication with just the user" do
+          expect(net_http_get).to receive(:basic_auth).with("username", nil)
+          subject.request(uri, options)
+        end
+      end
+
+      context "that contains cgi escaped characters" do
+        let(:uri) { URI("http://username%24@www.uri-to-fetch.com/api/v2/endpoint") }
+
+        it "should request basic authentication with the proper cgi compliant password user" do
+          expect(net_http_get).to receive(:basic_auth).with("username$", nil)
+          subject.request(uri, options)
+        end
+      end
+    end
+
+    context "when the request response causes a NoMethodError" do
+      before { allow(connection).to receive(:request).with(uri, net_http_get) { raise NoMethodError.new(message) } }
+
+      context "and the error message is about use_ssl=" do
+        let(:message) { "undefined method 'use_ssl='" }
+
+        it "should raise a LoadError about openssl" do
+          expect { subject.request(uri, options) }.to raise_error(LoadError, "cannot load such file -- openssl")
+        end
+      end
+
+      context "and the error message is not about use_ssl=" do
+        let(:message) { "undefined method 'undefined_method_call'" }
+
+        it "should raise the original NoMethodError" do
+          expect { subject.request(uri, options) }.to raise_error(NoMethodError, "undefined method 'undefined_method_call'")
+        end
+      end
+    end
+
+    context "when the request response causes a OpenSSL::SSL::SSLError" do
+      before { allow(connection).to receive(:request).with(uri, net_http_get) { raise OpenSSL::SSL::SSLError.new } }
+
+      it "should raise a LoadError about openssl" do
+        expect { subject.request(uri, options) }.to raise_error(Bundler::Fetcher::CertificateFailureError,
+          %r{Could not verify the SSL certificate for http://www.uri-to-fetch.com/api/v2/endpoint})
+      end
+    end
+
+    context "when the request response causes an error included in HTTP_ERRORS" do
+      let(:message) { nil }
+      let(:error)   { RuntimeError.new(message) }
+
+      before do
+        stub_const("Bundler::Fetcher::HTTP_ERRORS", [RuntimeError])
+        allow(connection).to receive(:request).with(uri, net_http_get) { raise error }
+      end
+
+      it "should trace log the error" do
+        allow(Bundler).to receive_message_chain(:ui, :debug)
+        expect(Bundler).to receive_message_chain(:ui, :trace).with(error)
+        expect { subject.request(uri, options) }.to raise_error(Bundler::HTTPError)
+      end
+
+      context "when error message is about the host being down" do
+        let(:message) { "host down: http://www.uri-to-fetch.com" }
+
+        it "should raise a Bundler::Fetcher::NetworkDownError" do
+          expect { subject.request(uri, options) }.to raise_error(Bundler::Fetcher::NetworkDownError,
+            /Could not reach host www.uri-to-fetch.com/)
+        end
+      end
+
+      context "when error message is about getaddrinfo issues" do
+        let(:message) { "getaddrinfo: nodename nor servname provided for http://www.uri-to-fetch.com" }
+
+        it "should raise a Bundler::Fetcher::NetworkDownError" do
+          expect { subject.request(uri, options) }.to raise_error(Bundler::Fetcher::NetworkDownError,
+            /Could not reach host www.uri-to-fetch.com/)
+        end
+      end
+
+      context "when error message is about neither host down or getaddrinfo" do
+        let(:message) { "other error about network" }
+
+        it "should raise a Bundler::HTTPError" do
+          expect { subject.request(uri, options) }.to raise_error(Bundler::HTTPError,
+            "Network error while fetching http://www.uri-to-fetch.com/api/v2/endpoint (other error about network)")
+        end
+
+        context "when the there are credentials provided in the request" do
+          let(:uri) { URI("http://username:password@www.uri-to-fetch.com/api/v2/endpoint") }
+          before do
+            allow(net_http_get).to receive(:basic_auth).with("username", "password")
+          end
+
+          it "should raise a Bundler::HTTPError that doesn't contain the password" do
+            expect { subject.request(uri, options) }.to raise_error(Bundler::HTTPError,
+              "Network error while fetching http://username@www.uri-to-fetch.com/api/v2/endpoint (other error about network)")
+          end
+        end
+      end
+
+      context "when error message is about no route to host" do
+        let(:message) { "Failed to open TCP connection to www.uri-to-fetch.com:443 " }
+
+        it "should raise a Bundler::Fetcher::HTTPError" do
+          expect { subject.request(uri, options) }.to raise_error(Bundler::HTTPError,
+            "Network error while fetching http://www.uri-to-fetch.com/api/v2/endpoint (#{message})")
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/fetcher/index_spec.rb b/spec/bundler/bundler/fetcher/index_spec.rb
new file mode 100644
index 0000000000..0cf0ae764e
--- /dev/null
+++ b/spec/bundler/bundler/fetcher/index_spec.rb
@@ -0,0 +1,99 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Fetcher::Index do
+  let(:downloader)  { nil }
+  let(:remote)      { nil }
+  let(:display_uri) { "http://sample_uri.com" }
+  let(:rubygems)    { double(:rubygems) }
+  let(:gem_names)   { %w[foo bar] }
+
+  subject { described_class.new(downloader, remote, display_uri) }
+
+  before { allow(Bundler).to receive(:rubygems).and_return(rubygems) }
+
+  it "fetches and returns the list of remote specs" do
+    expect(rubygems).to receive(:fetch_all_remote_specs) { nil }
+    subject.specs(gem_names)
+  end
+
+  context "error handling" do
+    shared_examples_for "the error is properly handled" do
+      let(:remote_uri) { URI("http://remote-uri.org") }
+      before do
+        allow(subject).to receive(:remote_uri).and_return(remote_uri)
+      end
+
+      context "when certificate verify failed" do
+        let(:error_message) { "certificate verify failed" }
+
+        it "should raise a Bundler::Fetcher::CertificateFailureError" do
+          expect { subject.specs(gem_names) }.to raise_error(Bundler::Fetcher::CertificateFailureError,
+            %r{Could not verify the SSL certificate for http://sample_uri.com})
+        end
+      end
+
+      context "when a 401 response occurs" do
+        let(:error_message) { "401" }
+
+        it "should raise a Bundler::Fetcher::AuthenticationRequiredError" do
+          expect { subject.specs(gem_names) }.to raise_error(Bundler::Fetcher::AuthenticationRequiredError,
+            %r{Authentication is required for http://remote-uri.org})
+        end
+      end
+
+      context "when a 403 response occurs" do
+        let(:error_message) { "403" }
+
+        before do
+          allow(remote_uri).to receive(:userinfo).and_return(userinfo)
+        end
+
+        context "and there was userinfo" do
+          let(:userinfo) { double(:userinfo) }
+
+          it "should raise a Bundler::Fetcher::BadAuthenticationError" do
+            expect { subject.specs(gem_names) }.to raise_error(Bundler::Fetcher::BadAuthenticationError,
+              %r{Bad username or password for http://remote-uri.org})
+          end
+        end
+
+        context "and there was no userinfo" do
+          let(:userinfo) { nil }
+
+          it "should raise a Bundler::Fetcher::AuthenticationRequiredError" do
+            expect { subject.specs(gem_names) }.to raise_error(Bundler::Fetcher::AuthenticationRequiredError,
+              %r{Authentication is required for http://remote-uri.org})
+          end
+        end
+      end
+
+      context "any other message is returned" do
+        let(:error_message) { "You get an error, you get an error!" }
+
+        before { allow(Bundler).to receive(:ui).and_return(double(:trace => nil)) }
+
+        it "should raise a Bundler::HTTPError" do
+          expect { subject.specs(gem_names) }.to raise_error(Bundler::HTTPError, "Could not fetch specs from http://sample_uri.com")
+        end
+      end
+    end
+
+    context "when a Gem::RemoteFetcher::FetchError occurs" do
+      before { allow(rubygems).to receive(:fetch_all_remote_specs) { raise Gem::RemoteFetcher::FetchError.new(error_message, nil) } }
+
+      it_behaves_like "the error is properly handled"
+    end
+
+    context "when a OpenSSL::SSL::SSLError occurs" do
+      before { allow(rubygems).to receive(:fetch_all_remote_specs) { raise OpenSSL::SSL::SSLError.new(error_message) } }
+
+      it_behaves_like "the error is properly handled"
+    end
+
+    context "when a Net::HTTPFatalError occurs" do
+      before { allow(rubygems).to receive(:fetch_all_remote_specs) { raise Net::HTTPFatalError.new(error_message, 404) } }
+
+      it_behaves_like "the error is properly handled"
+    end
+  end
+end
diff --git a/spec/bundler/bundler/fetcher_spec.rb b/spec/bundler/bundler/fetcher_spec.rb
new file mode 100644
index 0000000000..184b9efa64
--- /dev/null
+++ b/spec/bundler/bundler/fetcher_spec.rb
@@ -0,0 +1,161 @@
+# frozen_string_literal: true
+
+require "bundler/fetcher"
+
+RSpec.describe Bundler::Fetcher do
+  let(:uri) { URI("https://example.com") }
+  let(:remote) { double("remote", :uri => uri, :original_uri => nil) }
+
+  subject(:fetcher) { Bundler::Fetcher.new(remote) }
+
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new("root") }
+  end
+
+  describe "#connection" do
+    context "when Gem.configuration doesn't specify http_proxy" do
+      it "specify no http_proxy" do
+        expect(fetcher.http_proxy).to be_nil
+      end
+      it "consider environment vars when determine proxy" do
+        with_env_vars("HTTP_PROXY" => "http://proxy-example.com") do
+          expect(fetcher.http_proxy).to match("http://proxy-example.com")
+        end
+      end
+    end
+    context "when Gem.configuration specifies http_proxy " do
+      let(:proxy) { "http://proxy-example2.com" }
+      before do
+        allow(Bundler.rubygems.configuration).to receive(:[]).with(:http_proxy).and_return(proxy)
+      end
+      it "consider Gem.configuration when determine proxy" do
+        expect(fetcher.http_proxy).to match("http://proxy-example2.com")
+      end
+      it "consider Gem.configuration when determine proxy" do
+        with_env_vars("HTTP_PROXY" => "http://proxy-example.com") do
+          expect(fetcher.http_proxy).to match("http://proxy-example2.com")
+        end
+      end
+      context "when the proxy is :no_proxy" do
+        let(:proxy) { :no_proxy }
+        it "does not set a proxy" do
+          expect(fetcher.http_proxy).to be_nil
+        end
+      end
+    end
+
+    context "when a rubygems source mirror is set" do
+      let(:orig_uri) { URI("http://zombo.com") }
+      let(:remote_with_mirror) do
+        double("remote", :uri => uri, :original_uri => orig_uri, :anonymized_uri => uri)
+      end
+
+      let(:fetcher) { Bundler::Fetcher.new(remote_with_mirror) }
+
+      it "sets the 'X-Gemfile-Source' header containing the original source" do
+        expect(
+          fetcher.send(:connection).override_headers["X-Gemfile-Source"]
+        ).to eq("http://zombo.com")
+      end
+    end
+
+    context "when there is no rubygems source mirror set" do
+      let(:remote_no_mirror) do
+        double("remote", :uri => uri, :original_uri => nil, :anonymized_uri => uri)
+      end
+
+      let(:fetcher) { Bundler::Fetcher.new(remote_no_mirror) }
+
+      it "does not set the 'X-Gemfile-Source' header" do
+        expect(fetcher.send(:connection).override_headers["X-Gemfile-Source"]).to be_nil
+      end
+    end
+
+    context "when there are proxy environment variable(s) set" do
+      it "consider http_proxy" do
+        with_env_vars("HTTP_PROXY" => "http://proxy-example3.com") do
+          expect(fetcher.http_proxy).to match("http://proxy-example3.com")
+        end
+      end
+      it "consider no_proxy" do
+        with_env_vars("HTTP_PROXY" => "http://proxy-example4.com", "NO_PROXY" => ".example.com,.example.net") do
+          expect(
+            fetcher.send(:connection).no_proxy
+          ).to eq([".example.com", ".example.net"])
+        end
+      end
+    end
+
+    context "when no ssl configuration is set" do
+      it "no cert" do
+        expect(fetcher.send(:connection).cert).to be_nil
+        expect(fetcher.send(:connection).key).to be_nil
+      end
+    end
+
+    context "when bunder ssl ssl configuration is set" do
+      before do
+        cert = File.join(Spec::Path.tmpdir, "cert")
+        File.open(cert, "w") {|f| f.write "PEM" }
+        allow(Bundler.settings).to receive(:[]).and_return(nil)
+        allow(Bundler.settings).to receive(:[]).with(:ssl_client_cert).and_return(cert)
+        expect(OpenSSL::X509::Certificate).to receive(:new).with("PEM").and_return("cert")
+        expect(OpenSSL::PKey::RSA).to receive(:new).with("PEM").and_return("key")
+      end
+      after do
+        FileUtils.rm File.join(Spec::Path.tmpdir, "cert")
+      end
+      it "use bundler configuration" do
+        expect(fetcher.send(:connection).cert).to eq("cert")
+        expect(fetcher.send(:connection).key).to eq("key")
+      end
+    end
+
+    context "when gem ssl configuration is set" do
+      before do
+        allow(Bundler.rubygems.configuration).to receive_messages(
+          :http_proxy => nil,
+          :ssl_client_cert => "cert",
+          :ssl_ca_cert => "ca"
+        )
+        expect(File).to receive(:read).and_return("")
+        expect(OpenSSL::X509::Certificate).to receive(:new).and_return("cert")
+        expect(OpenSSL::PKey::RSA).to receive(:new).and_return("key")
+        store = double("ca store")
+        expect(store).to receive(:add_file)
+        expect(OpenSSL::X509::Store).to receive(:new).and_return(store)
+      end
+      it "use gem configuration" do
+        expect(fetcher.send(:connection).cert).to eq("cert")
+        expect(fetcher.send(:connection).key).to eq("key")
+      end
+    end
+  end
+
+  describe "#user_agent" do
+    it "builds user_agent with current ruby version and Bundler settings" do
+      allow(Bundler.settings).to receive(:all).and_return(%w[foo bar])
+      expect(fetcher.user_agent).to match(%r{bundler/(\d.)})
+      expect(fetcher.user_agent).to match(%r{rubygems/(\d.)})
+      expect(fetcher.user_agent).to match(%r{ruby/(\d.)})
+      expect(fetcher.user_agent).to match(%r{options/foo,bar})
+    end
+
+    describe "include CI information" do
+      it "from one CI" do
+        with_env_vars("JENKINS_URL" => "foo") do
+          ci_part = fetcher.user_agent.split(" ").find {|x| x.match(%r{\Aci/}) }
+          expect(ci_part).to match("jenkins")
+        end
+      end
+
+      it "from many CI" do
+        with_env_vars("TRAVIS" => "foo", "CI_NAME" => "my_ci") do
+          ci_part = fetcher.user_agent.split(" ").find {|x| x.match(%r{\Aci/}) }
+          expect(ci_part).to match("travis")
+          expect(ci_part).to match("my_ci")
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/friendly_errors_spec.rb b/spec/bundler/bundler/friendly_errors_spec.rb
new file mode 100644
index 0000000000..2a1be491ef
--- /dev/null
+++ b/spec/bundler/bundler/friendly_errors_spec.rb
@@ -0,0 +1,270 @@
+# frozen_string_literal: true
+
+require "bundler"
+require "bundler/friendly_errors"
+require "cgi"
+
+RSpec.describe Bundler, "friendly errors" do
+  context "with invalid YAML in .gemrc" do
+    before do
+      File.open(Gem.configuration.config_file_name, "w") do |f|
+        f.write "invalid: yaml: hah"
+      end
+    end
+
+    after do
+      FileUtils.rm(Gem.configuration.config_file_name)
+    end
+
+    it "reports a relevant friendly error message", :ruby => ">= 1.9", :rubygems => "< 2.5.0" do
+      gemfile <<-G
+        source "file://#{gem_repo1}"
+        gem "rack"
+      G
+
+      bundle :install, :env => { "DEBUG" => true }
+
+      expect(out).to include("Your RubyGems configuration")
+      expect(out).to include("invalid YAML syntax")
+      expect(out).to include("Psych::SyntaxError")
+      expect(out).not_to include("ERROR REPORT TEMPLATE")
+      expect(exitstatus).to eq(25) if exitstatus
+    end
+
+    it "reports a relevant friendly error message", :ruby => ">= 1.9", :rubygems => ">= 2.5.0" do
+      gemfile <<-G
+        source "file://#{gem_repo1}"
+        gem "rack"
+      G
+
+      bundle :install, :env => { "DEBUG" => true }
+
+      expect(last_command.stderr).to include("Failed to load #{home(".gemrc")}")
+      expect(exitstatus).to eq(0) if exitstatus
+    end
+  end
+
+  it "calls log_error in case of exception" do
+    exception = Exception.new
+    expect(Bundler::FriendlyErrors).to receive(:exit_status).with(exception).and_return(1)
+    expect do
+      Bundler.with_friendly_errors do
+        raise exception
+      end
+    end.to raise_error(SystemExit)
+  end
+
+  it "calls exit_status on exception" do
+    exception = Exception.new
+    expect(Bundler::FriendlyErrors).to receive(:log_error).with(exception)
+    expect do
+      Bundler.with_friendly_errors do
+        raise exception
+      end
+    end.to raise_error(SystemExit)
+  end
+
+  describe "#log_error" do
+    shared_examples "Bundler.ui receive error" do |error, message|
+      it "" do
+        expect(Bundler.ui).to receive(:error).with(message || error.message)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+
+    shared_examples "Bundler.ui receive trace" do |error|
+      it "" do
+        expect(Bundler.ui).to receive(:trace).with(error)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+
+    context "YamlSyntaxError" do
+      it_behaves_like "Bundler.ui receive error", Bundler::YamlSyntaxError.new(StandardError.new, "sample_message")
+
+      it "Bundler.ui receive trace" do
+        std_error = StandardError.new
+        exception = Bundler::YamlSyntaxError.new(std_error, "sample_message")
+        expect(Bundler.ui).to receive(:trace).with(std_error)
+        Bundler::FriendlyErrors.log_error(exception)
+      end
+    end
+
+    context "Dsl::DSLError, GemspecError" do
+      it_behaves_like "Bundler.ui receive error", Bundler::Dsl::DSLError.new("description", "dsl_path", "backtrace")
+      it_behaves_like "Bundler.ui receive error", Bundler::GemspecError.new
+    end
+
+    context "GemRequireError" do
+      let(:orig_error) { StandardError.new }
+      let(:error) { Bundler::GemRequireError.new(orig_error, "sample_message") }
+
+      before do
+        allow(orig_error).to receive(:backtrace).and_return([])
+      end
+
+      it "Bundler.ui receive error" do
+        expect(Bundler.ui).to receive(:error).with(error.message)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+
+      it "writes to Bundler.ui.trace" do
+        expect(Bundler.ui).to receive(:trace).with(orig_error, nil, true)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+
+    context "BundlerError" do
+      it "Bundler.ui receive error" do
+        error = Bundler::BundlerError.new
+        expect(Bundler.ui).to receive(:error).with(error.message, :wrap => true)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+      it_behaves_like "Bundler.ui receive trace", Bundler::BundlerError.new
+    end
+
+    context "Thor::Error" do
+      it_behaves_like "Bundler.ui receive error", Bundler::Thor::Error.new
+    end
+
+    context "LoadError" do
+      let(:error) { LoadError.new("cannot load such file -- openssl") }
+
+      it "Bundler.ui receive error" do
+        expect(Bundler.ui).to receive(:error).with("\nCould not load OpenSSL.")
+        Bundler::FriendlyErrors.log_error(error)
+      end
+
+      it "Bundler.ui receive warn" do
+        expect(Bundler.ui).to receive(:warn).with(any_args, :wrap => true)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+
+      it "Bundler.ui receive trace" do
+        expect(Bundler.ui).to receive(:trace).with(error)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+
+    context "Interrupt" do
+      it "Bundler.ui receive error" do
+        expect(Bundler.ui).to receive(:error).with("\nQuitting...")
+        Bundler::FriendlyErrors.log_error(Interrupt.new)
+      end
+      it_behaves_like "Bundler.ui receive trace", Interrupt.new
+    end
+
+    context "Gem::InvalidSpecificationException" do
+      it "Bundler.ui receive error" do
+        error = Gem::InvalidSpecificationException.new
+        expect(Bundler.ui).to receive(:error).with(error.message, :wrap => true)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+
+    context "SystemExit" do
+      # Does nothing
+    end
+
+    context "Java::JavaLang::OutOfMemoryError" do
+      module Java
+        module JavaLang
+          class OutOfMemoryError < StandardError; end
+        end
+      end
+
+      it "Bundler.ui receive error" do
+        error = Java::JavaLang::OutOfMemoryError.new
+        expect(Bundler.ui).to receive(:error).with(/JVM has run out of memory/)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+
+    context "unexpected error" do
+      it "calls request_issue_report_for with error" do
+        error = StandardError.new
+        expect(Bundler::FriendlyErrors).to receive(:request_issue_report_for).with(error)
+        Bundler::FriendlyErrors.log_error(error)
+      end
+    end
+  end
+
+  describe "#exit_status" do
+    it "calls status_code for BundlerError" do
+      error = Bundler::BundlerError.new
+      expect(error).to receive(:status_code).and_return("sample_status_code")
+      expect(Bundler::FriendlyErrors.exit_status(error)).to eq("sample_status_code")
+    end
+
+    it "returns 15 for Thor::Error" do
+      error = Bundler::Thor::Error.new
+      expect(Bundler::FriendlyErrors.exit_status(error)).to eq(15)
+    end
+
+    it "calls status for SystemExit" do
+      error = SystemExit.new
+      expect(error).to receive(:status).and_return("sample_status")
+      expect(Bundler::FriendlyErrors.exit_status(error)).to eq("sample_status")
+    end
+
+    it "returns 1 in other cases" do
+      error = StandardError.new
+      expect(Bundler::FriendlyErrors.exit_status(error)).to eq(1)
+    end
+  end
+
+  describe "#request_issue_report_for" do
+    it "calls relevant methods for Bundler.ui" do
+      expect(Bundler.ui).to receive(:info)
+      expect(Bundler.ui).to receive(:error)
+      expect(Bundler.ui).to receive(:warn)
+      Bundler::FriendlyErrors.request_issue_report_for(StandardError.new)
+    end
+
+    it "includes error class, message and backlog" do
+      error = StandardError.new
+      allow(Bundler::FriendlyErrors).to receive(:issues_url).and_return("")
+
+      expect(error).to receive(:class).at_least(:once)
+      expect(error).to receive(:message).at_least(:once)
+      expect(error).to receive(:backtrace).at_least(:once)
+      Bundler::FriendlyErrors.request_issue_report_for(error)
+    end
+  end
+
+  describe "#issues_url" do
+    it "generates a search URL for the exception message" do
+      exception = Exception.new("Exception message")
+
+      expect(Bundler::FriendlyErrors.issues_url(exception)).to eq("https://github.com/bundler/bundler/search?q=Exception+message&type=Issues")
+    end
+
+    it "generates a search URL for only the first line of a multi-line exception message" do
+      exception = Exception.new(<<END)
+First line of the exception message
+Second line of the exception message
+END
+
+      expect(Bundler::FriendlyErrors.issues_url(exception)).to eq("https://github.com/bundler/bundler/search?q=First+line+of+the+exception+message&type=Issues")
+    end
+
+    it "generates the url without colons" do
+      exception = Exception.new(<<END)
+Exception ::: with ::: colons :::
+END
+      issues_url = Bundler::FriendlyErrors.issues_url(exception)
+      expect(issues_url).not_to include("%3A")
+      expect(issues_url).to eq("https://github.com/bundler/bundler/search?q=#{CGI.escape("Exception     with     colons    ")}&type=Issues")
+    end
+
+    it "removes information after - for Errono::EACCES" do
+      exception = Exception.new(<<END)
+Errno::EACCES: Permission denied @ dir_s_mkdir - /Users/foo/bar/
+END
+      allow(exception).to receive(:is_a?).with(Errno).and_return(true)
+      issues_url = Bundler::FriendlyErrors.issues_url(exception)
+      expect(issues_url).not_to include("/Users/foo/bar")
+      expect(issues_url).to eq("https://github.com/bundler/bundler/search?q=#{CGI.escape("Errno  EACCES  Permission denied @ dir_s_mkdir ")}&type=Issues")
+    end
+  end
+end
diff --git a/spec/bundler/bundler/gem_helper_spec.rb b/spec/bundler/bundler/gem_helper_spec.rb
new file mode 100644
index 0000000000..a627129fe3
--- /dev/null
+++ b/spec/bundler/bundler/gem_helper_spec.rb
@@ -0,0 +1,351 @@
+# frozen_string_literal: true
+
+require "rake"
+require "bundler/gem_helper"
+
+RSpec.describe Bundler::GemHelper do
+  let(:app_name) { "lorem__ipsum" }
+  let(:app_path) { bundled_app app_name }
+  let(:app_gemspec_path) { app_path.join("#{app_name}.gemspec") }
+
+  before(:each) do
+    global_config "BUNDLE_GEM__MIT" => "false", "BUNDLE_GEM__TEST" => "false", "BUNDLE_GEM__COC" => "false"
+    bundle "gem #{app_name}"
+  end
+
+  context "determining gemspec" do
+    subject { Bundler::GemHelper.new(app_path) }
+
+    context "fails" do
+      it "when there is no gemspec" do
+        FileUtils.rm app_gemspec_path
+        expect { subject }.to raise_error(/Unable to determine name/)
+      end
+
+      it "when there are two gemspecs and the name isn't specified" do
+        FileUtils.touch app_path.join("#{app_name}-2.gemspec")
+        expect { subject }.to raise_error(/Unable to determine name/)
+      end
+    end
+
+    context "interpolates the name" do
+      before do
+        # Remove exception that prevents public pushes on older RubyGems versions
+        if Gem::Version.new(Gem::VERSION) < Gem::Version.new("2.0")
+          content = File.read(app_gemspec_path)
+          content.sub!(/raise "RubyGems 2\.0 or newer.*/, "")
+          File.open(app_gemspec_path, "w") {|f| f.write(content) }
+        end
+      end
+
+      it "when there is only one gemspec" do
+        expect(subject.gemspec.name).to eq(app_name)
+      end
+
+      it "for a hidden gemspec" do
+        FileUtils.mv app_gemspec_path, app_path.join(".gemspec")
+        expect(subject.gemspec.name).to eq(app_name)
+      end
+    end
+
+    it "handles namespaces and converts them to CamelCase" do
+      bundle "gem #{app_name}-foo_bar"
+      underscore_path = bundled_app "#{app_name}-foo_bar"
+
+      lib = underscore_path.join("lib/#{app_name}/foo_bar.rb").read
+      expect(lib).to include("module LoremIpsum")
+      expect(lib).to include("module FooBar")
+    end
+  end
+
+  context "gem management" do
+    def mock_confirm_message(message)
+      expect(Bundler.ui).to receive(:confirm).with(message)
+    end
+
+    def mock_build_message(name, version)
+      message = "#{name} #{version} built to pkg/#{name}-#{version}.gem."
+      mock_confirm_message message
+    end
+
+    subject! { Bundler::GemHelper.new(app_path) }
+    let(:app_version) { "0.1.0" }
+    let(:app_gem_dir) { app_path.join("pkg") }
+    let(:app_gem_path) { app_gem_dir.join("#{app_name}-#{app_version}.gem") }
+    let(:app_gemspec_content) { remove_push_guard(File.read(app_gemspec_path)) }
+
+    before(:each) do
+      content = app_gemspec_content.gsub("TODO: ", "")
+      content.sub!(/homepage\s+= ".*"/, 'homepage = ""')
+      content.gsub!(/spec\.metadata.+\n/, "")
+      File.open(app_gemspec_path, "w") {|file| file << content }
+    end
+
+    def remove_push_guard(gemspec_content)
+      # Remove exception that prevents public pushes on older RubyGems versions
+      if Gem::Version.new(Gem::VERSION) < Gem::Version.new("2.0")
+        gemspec_content.sub!(/raise "RubyGems 2\.0 or newer.*/, "")
+      end
+      gemspec_content
+    end
+
+    it "uses a shell UI for output" do
+      expect(Bundler.ui).to be_a(Bundler::UI::Shell)
+    end
+
+    describe "#install" do
+      let!(:rake_application) { Rake.application }
+
+      before(:each) do
+        Rake.application = Rake::Application.new
+      end
+
+      after(:each) do
+        Rake.application = rake_application
+      end
+
+      context "defines Rake tasks" do
+        let(:task_names) do
+          %w[build install release release:guard_clean
+             release:source_control_push release:rubygem_push]
+        end
+
+        context "before installation" do
+          it "raises an error with appropriate message" do
+            task_names.each do |name|
+              expect { Rake.application[name] }.
+                to raise_error(/^Don't know how to build task '#{name}'/)
+            end
+          end
+        end
+
+        context "after installation" do
+          before do
+            subject.install
+          end
+
+          it "adds Rake tasks successfully" do
+            task_names.each do |name|
+              expect { Rake.application[name] }.not_to raise_error
+              expect(Rake.application[name]).to be_instance_of Rake::Task
+            end
+          end
+
+          it "provides a way to access the gemspec object" do
+            expect(subject.gemspec.name).to eq(app_name)
+          end
+        end
+      end
+    end
+
+    describe "#build_gem" do
+      context "when build failed" do
+        it "raises an error with appropriate message" do
+          # break the gemspec by adding back the TODOs
+          File.open(app_gemspec_path, "w") {|file| file << app_gemspec_content }
+          expect { subject.build_gem }.to raise_error(/TODO/)
+        end
+      end
+
+      context "when build was successful" do
+        it "creates .gem file" do
+          mock_build_message app_name, app_version
+          subject.build_gem
+          expect(app_gem_path).to exist
+        end
+      end
+    end
+
+    describe "#install_gem" do
+      context "when installation was successful" do
+        it "gem is installed" do
+          mock_build_message app_name, app_version
+          mock_confirm_message "#{app_name} (#{app_version}) installed."
+          subject.install_gem(nil, :local)
+          expect(app_gem_path).to exist
+          gem_command! :list
+          expect(out).to include("#{app_name} (#{app_version})")
+        end
+      end
+
+      context "when installation fails" do
+        it "raises an error with appropriate message" do
+          # create empty gem file in order to simulate install failure
+          allow(subject).to receive(:build_gem) do
+            FileUtils.mkdir_p(app_gem_dir)
+            FileUtils.touch app_gem_path
+            app_gem_path
+          end
+          expect { subject.install_gem }.to raise_error(/Couldn't install gem/)
+        end
+      end
+    end
+
+    describe "rake release" do
+      let!(:rake_application) { Rake.application }
+
+      before(:each) do
+        Rake.application = Rake::Application.new
+        subject.install
+      end
+
+      after(:each) do
+        Rake.application = rake_application
+      end
+
+      before do
+        Dir.chdir(app_path) do
+          `git init`
+          `git config user.email "you@example.com"`
+          `git config user.name "name"`
+          `git config push.default simple`
+        end
+
+        # silence messages
+        allow(Bundler.ui).to receive(:confirm)
+        allow(Bundler.ui).to receive(:error)
+      end
+
+      context "fails" do
+        it "when there are unstaged files" do
+          expect { Rake.application["release"].invoke }.
+            to raise_error("There are files that need to be committed first.")
+        end
+
+        it "when there are uncommitted files" do
+          Dir.chdir(app_path) { `git add .` }
+          expect { Rake.application["release"].invoke }.
+            to raise_error("There are files that need to be committed first.")
+        end
+
+        it "when there is no git remote" do
+          Dir.chdir(app_path) { `git commit -a -m "initial commit"` }
+          expect { Rake.application["release"].invoke }.to raise_error(RuntimeError)
+        end
+      end
+
+      context "succeeds" do
+        before do
+          Dir.chdir(gem_repo1) { `git init --bare` }
+          Dir.chdir(app_path) do
+            `git remote add origin file://#{gem_repo1}`
+            `git commit -a -m "initial commit"`
+          end
+        end
+
+        it "on releasing" do
+          mock_build_message app_name, app_version
+          mock_confirm_message "Tagged v#{app_version}."
+          mock_confirm_message "Pushed git commits and tags."
+          expect(subject).to receive(:rubygem_push).with(app_gem_path.to_s)
+
+          Dir.chdir(app_path) { sys_exec("git push -u origin master") }
+
+          Rake.application["release"].invoke
+        end
+
+        it "even if tag already exists" do
+          mock_build_message app_name, app_version
+          mock_confirm_message "Tag v#{app_version} has already been created."
+          expect(subject).to receive(:rubygem_push).with(app_gem_path.to_s)
+
+          Dir.chdir(app_path) do
+            `git tag -a -m \"Version #{app_version}\" v#{app_version}`
+          end
+
+          Rake.application["release"].invoke
+        end
+      end
+    end
+
+    describe "release:rubygem_push" do
+      let!(:rake_application) { Rake.application }
+
+      before(:each) do
+        Rake.application = Rake::Application.new
+        subject.install
+        allow(subject).to receive(:sh)
+      end
+
+      after(:each) do
+        Rake.application = rake_application
+      end
+
+      before do
+        Dir.chdir(app_path) do
+          `git init`
+          `git config user.email "you@example.com"`
+          `git config user.name "name"`
+          `git config push.default simple`
+        end
+
+        # silence messages
+        allow(Bundler.ui).to receive(:confirm)
+        allow(Bundler.ui).to receive(:error)
+
+        credentials = double("credentials", "file?" => true)
+        allow(Bundler.user_home).to receive(:join).
+          with(".gem/credentials").and_return(credentials)
+      end
+
+      describe "success messaging" do
+        context "No allowed_push_host set" do
+          before do
+            allow(subject).to receive(:allowed_push_host).and_return(nil)
+          end
+
+          around do |example|
+            orig_host = ENV["RUBYGEMS_HOST"]
+            ENV["RUBYGEMS_HOST"] = rubygems_host_env
+
+            example.run
+
+            ENV["RUBYGEMS_HOST"] = orig_host
+          end
+
+          context "RUBYGEMS_HOST env var is set" do
+            let(:rubygems_host_env) { "https://custom.env.gemhost.com" }
+
+            it "should report successful push to the host from the environment" do
+              mock_confirm_message "Pushed #{app_name} #{app_version} to #{rubygems_host_env}"
+
+              Rake.application["release:rubygem_push"].invoke
+            end
+          end
+
+          context "RUBYGEMS_HOST env var is not set" do
+            let(:rubygems_host_env) { nil }
+
+            it "should report successful push to rubygems.org" do
+              mock_confirm_message "Pushed #{app_name} #{app_version} to rubygems.org"
+
+              Rake.application["release:rubygem_push"].invoke
+            end
+          end
+
+          context "RUBYGEMS_HOST env var is an empty string" do
+            let(:rubygems_host_env) { "" }
+
+            it "should report successful push to rubygems.org" do
+              mock_confirm_message "Pushed #{app_name} #{app_version} to rubygems.org"
+
+              Rake.application["release:rubygem_push"].invoke
+            end
+          end
+        end
+
+        context "allowed_push_host set in gemspec" do
+          before do
+            allow(subject).to receive(:allowed_push_host).and_return("https://my.gemhost.com")
+          end
+
+          it "should report successful push to the allowed gem host" do
+            mock_confirm_message "Pushed #{app_name} #{app_version} to https://my.gemhost.com"
+
+            Rake.application["release:rubygem_push"].invoke
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/gem_version_promoter_spec.rb b/spec/bundler/bundler/gem_version_promoter_spec.rb
new file mode 100644
index 0000000000..01e0232fba
--- /dev/null
+++ b/spec/bundler/bundler/gem_version_promoter_spec.rb
@@ -0,0 +1,179 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::GemVersionPromoter do
+  context "conservative resolver" do
+    def versions(result)
+      result.flatten.map(&:version).map(&:to_s)
+    end
+
+    def make_instance(*args)
+      @gvp = Bundler::GemVersionPromoter.new(*args).tap do |gvp|
+        gvp.class.class_eval { public :filter_dep_specs, :sort_dep_specs }
+      end
+    end
+
+    def unlocking(options)
+      make_instance(Bundler::SpecSet.new([]), ["foo"]).tap do |p|
+        p.level = options[:level] if options[:level]
+        p.strict = options[:strict] if options[:strict]
+      end
+    end
+
+    def keep_locked(options)
+      make_instance(Bundler::SpecSet.new([]), ["bar"]).tap do |p|
+        p.level = options[:level] if options[:level]
+        p.strict = options[:strict] if options[:strict]
+      end
+    end
+
+    def build_spec_groups(name, versions)
+      versions.map do |v|
+        Bundler::Resolver::SpecGroup.new(build_spec(name, v))
+      end
+    end
+
+    # Rightmost (highest array index) in result is most preferred.
+    # Leftmost (lowest array index) in result is least preferred.
+    # `build_spec_groups` has all versions of gem in index.
+    # `build_spec` is the version currently in the .lock file.
+    #
+    # In default (not strict) mode, all versions in the index will
+    # be returned, allowing Bundler the best chance to resolve all
+    # dependencies, but sometimes resulting in upgrades that some
+    # would not consider conservative.
+    context "filter specs (strict) level patch" do
+      it "when keeping build_spec, keep current, next release" do
+        keep_locked(:level => :patch)
+        res = @gvp.filter_dep_specs(
+          build_spec_groups("foo", %w[1.7.8 1.7.9 1.8.0]),
+          build_spec("foo", "1.7.8").first
+        )
+        expect(versions(res)).to eq %w[1.7.9 1.7.8]
+      end
+
+      it "when unlocking prefer next release first" do
+        unlocking(:level => :patch)
+        res = @gvp.filter_dep_specs(
+          build_spec_groups("foo", %w[1.7.8 1.7.9 1.8.0]),
+          build_spec("foo", "1.7.8").first
+        )
+        expect(versions(res)).to eq %w[1.7.8 1.7.9]
+      end
+
+      it "when unlocking keep current when already at latest release" do
+        unlocking(:level => :patch)
+        res = @gvp.filter_dep_specs(
+          build_spec_groups("foo", %w[1.7.9 1.8.0 2.0.0]),
+          build_spec("foo", "1.7.9").first
+        )
+        expect(versions(res)).to eq %w[1.7.9]
+      end
+    end
+
+    context "filter specs (strict) level minor" do
+      it "when unlocking favor next releases, remove minor and major increases" do
+        unlocking(:level => :minor)
+        res = @gvp.filter_dep_specs(
+          build_spec_groups("foo", %w[0.2.0 0.3.0 0.3.1 0.9.0 1.0.0 2.0.0 2.0.1]),
+          build_spec("foo", "0.2.0").first
+        )
+        expect(versions(res)).to eq %w[0.2.0 0.3.0 0.3.1 0.9.0]
+      end
+
+      it "when keep locked, keep current, then favor next release, remove minor and major increases" do
+        keep_locked(:level => :minor)
+        res = @gvp.filter_dep_specs(
+          build_spec_groups("foo", %w[0.2.0 0.3.0 0.3.1 0.9.0 1.0.0 2.0.0 2.0.1]),
+          build_spec("foo", "0.2.0").first
+        )
+        expect(versions(res)).to eq %w[0.3.0 0.3.1 0.9.0 0.2.0]
+      end
+    end
+
+    context "sort specs (not strict) level patch" do
+      it "when not unlocking, same order but make sure build_spec version is most preferred to stay put" do
+        keep_locked(:level => :patch)
+        res = @gvp.sort_dep_specs(
+          build_spec_groups("foo", %w[1.5.4 1.6.5 1.7.6 1.7.7 1.7.8 1.7.9 1.8.0 1.8.1 2.0.0 2.0.1]),
+          build_spec("foo", "1.7.7").first
+        )
+        expect(versions(res)).to eq %w[1.5.4 1.6.5 1.7.6 2.0.0 2.0.1 1.8.0 1.8.1 1.7.8 1.7.9 1.7.7]
+      end
+
+      it "when unlocking favor next release, then current over minor increase" do
+        unlocking(:level => :patch)
+        res = @gvp.sort_dep_specs(
+          build_spec_groups("foo", %w[1.7.7 1.7.8 1.7.9 1.8.0]),
+          build_spec("foo", "1.7.8").first
+        )
+        expect(versions(res)).to eq %w[1.7.7 1.8.0 1.7.8 1.7.9]
+      end
+
+      it "when unlocking do proper integer comparison, not string" do
+        unlocking(:level => :patch)
+        res = @gvp.sort_dep_specs(
+          build_spec_groups("foo", %w[1.7.7 1.7.8 1.7.9 1.7.15 1.8.0]),
+          build_spec("foo", "1.7.8").first
+        )
+        expect(versions(res)).to eq %w[1.7.7 1.8.0 1.7.8 1.7.9 1.7.15]
+      end
+
+      it "leave current when unlocking but already at latest release" do
+        unlocking(:level => :patch)
+        res = @gvp.sort_dep_specs(
+          build_spec_groups("foo", %w[1.7.9 1.8.0 2.0.0]),
+          build_spec("foo", "1.7.9").first
+        )
+        expect(versions(res)).to eq %w[2.0.0 1.8.0 1.7.9]
+      end
+    end
+
+    context "sort specs (not strict) level minor" do
+      it "when unlocking favor next release, then minor increase over current" do
+        unlocking(:level => :minor)
+        res = @gvp.sort_dep_specs(
+          build_spec_groups("foo", %w[0.2.0 0.3.0 0.3.1 0.9.0 1.0.0 2.0.0 2.0.1]),
+          build_spec("foo", "0.2.0").first
+        )
+        expect(versions(res)).to eq %w[2.0.0 2.0.1 1.0.0 0.2.0 0.3.0 0.3.1 0.9.0]
+      end
+    end
+
+    context "level error handling" do
+      subject { Bundler::GemVersionPromoter.new }
+
+      it "should raise if not major, minor or patch is passed" do
+        expect { subject.level = :minjor }.to raise_error ArgumentError
+      end
+
+      it "should raise if invalid classes passed" do
+        [123, nil].each do |value|
+          expect { subject.level = value }.to raise_error ArgumentError
+        end
+      end
+
+      it "should accept major, minor patch symbols" do
+        [:major, :minor, :patch].each do |value|
+          subject.level = value
+          expect(subject.level).to eq value
+        end
+      end
+
+      it "should accept major, minor patch strings" do
+        %w[major minor patch].each do |value|
+          subject.level = value
+          expect(subject.level).to eq value.to_sym
+        end
+      end
+    end
+
+    context "debug output" do
+      it "should not kerblooie on its own debug output" do
+        gvp = unlocking(:level => :patch)
+        dep = Bundler::DepProxy.new(dep("foo", "1.2.0").first, "ruby")
+        result = gvp.send(:debug_format_result, dep, build_spec_groups("foo", %w[1.2.0 1.3.0]))
+        expect(result.class).to eq Array
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/index_spec.rb b/spec/bundler/bundler/index_spec.rb
new file mode 100644
index 0000000000..0f3f6e4944
--- /dev/null
+++ b/spec/bundler/bundler/index_spec.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Index do
+  let(:specs) { [] }
+  subject { described_class.build {|i| i.use(specs) } }
+
+  context "specs with a nil platform" do
+    let(:spec) do
+      Gem::Specification.new do |s|
+        s.name = "json"
+        s.version = "1.8.3"
+        allow(s).to receive(:platform).and_return(nil)
+      end
+    end
+    let(:specs) { [spec] }
+
+    describe "#search_by_spec" do
+      it "finds the spec when a nil platform is specified" do
+        expect(subject.search(spec)).to eq([spec])
+      end
+
+      it "finds the spec when a ruby platform is specified" do
+        query = spec.dup.tap {|s| s.platform = "ruby" }
+        expect(subject.search(query)).to eq([spec])
+      end
+    end
+  end
+
+  context "with specs that include development dependencies" do
+    let(:specs) { [*build_spec("a", "1.0.0") {|s| s.development("b", "~> 1.0") }] }
+
+    it "does not include b in #dependency_names" do
+      expect(subject.dependency_names).not_to include("b")
+    end
+  end
+end
diff --git a/spec/bundler/bundler/installer/gem_installer_spec.rb b/spec/bundler/bundler/installer/gem_installer_spec.rb
new file mode 100644
index 0000000000..7340a3acc0
--- /dev/null
+++ b/spec/bundler/bundler/installer/gem_installer_spec.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+require "bundler/installer/gem_installer"
+
+RSpec.describe Bundler::GemInstaller do
+  let(:installer) { instance_double("Installer") }
+  let(:spec_source) { instance_double("SpecSource") }
+  let(:spec) { instance_double("Specification", :name => "dummy", :version => "0.0.1", :loaded_from => "dummy", :source => spec_source) }
+
+  subject { described_class.new(spec, installer) }
+
+  context "spec_settings is nil" do
+    it "invokes install method with empty build_args", :rubygems => ">= 2" do
+      allow(spec_source).to receive(:install).with(spec, :force => false, :ensure_builtin_gems_cached => false, :build_args => [])
+      subject.install_from_spec
+    end
+  end
+
+  context "spec_settings is build option" do
+    it "invokes install method with build_args", :rubygems => ">= 2" do
+      allow(Bundler.settings).to receive(:[]).with(:bin)
+      allow(Bundler.settings).to receive(:[]).with(:inline)
+      allow(Bundler.settings).to receive(:[]).with(:forget_cli_options)
+      allow(Bundler.settings).to receive(:[]).with("build.dummy").and_return("--with-dummy-config=dummy")
+      expect(spec_source).to receive(:install).with(spec, :force => false, :ensure_builtin_gems_cached => false, :build_args => ["--with-dummy-config=dummy"])
+      subject.install_from_spec
+    end
+  end
+end
diff --git a/spec/bundler/bundler/installer/parallel_installer_spec.rb b/spec/bundler/bundler/installer/parallel_installer_spec.rb
new file mode 100644
index 0000000000..ace5c1a23a
--- /dev/null
+++ b/spec/bundler/bundler/installer/parallel_installer_spec.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+require "bundler/installer/parallel_installer"
+
+RSpec.describe Bundler::ParallelInstaller do
+  let(:installer) { instance_double("Installer") }
+  let(:all_specs) { [] }
+  let(:size) { 1 }
+  let(:standalone) { false }
+  let(:force) { false }
+
+  subject { described_class.new(installer, all_specs, size, standalone, force) }
+
+  context "when dependencies that are not on the overall installation list are the only ones not installed" do
+    let(:all_specs) do
+      [
+        build_spec("alpha", "1.0") {|s| s.runtime "a", "1" },
+      ].flatten
+    end
+
+    it "prints a warning" do
+      expect(Bundler.ui).to receive(:warn).with(<<-W.strip)
+Your lockfile was created by an old Bundler that left some things out.
+You can fix this by adding the missing gems to your Gemfile, running bundle install, and then removing the gems from your Gemfile.
+The missing gems are:
+* a depended upon by alpha
+      W
+      subject.check_for_corrupt_lockfile
+    end
+
+    context "when size > 1" do
+      let(:size) { 500 }
+
+      it "prints a warning and sets size to 1" do
+        expect(Bundler.ui).to receive(:warn).with(<<-W.strip)
+Your lockfile was created by an old Bundler that left some things out.
+Because of the missing DEPENDENCIES, we can only install gems one at a time, instead of installing 500 at a time.
+You can fix this by adding the missing gems to your Gemfile, running bundle install, and then removing the gems from your Gemfile.
+The missing gems are:
+* a depended upon by alpha
+        W
+        subject.check_for_corrupt_lockfile
+        expect(subject.size).to eq(1)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/installer/spec_installation_spec.rb b/spec/bundler/bundler/installer/spec_installation_spec.rb
new file mode 100644
index 0000000000..a9cf09a372
--- /dev/null
+++ b/spec/bundler/bundler/installer/spec_installation_spec.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+require "bundler/installer/parallel_installer"
+
+RSpec.describe Bundler::ParallelInstaller::SpecInstallation do
+  let!(:dep) do
+    a_spec = Object.new
+    def a_spec.name
+      "I like tests"
+    end
+    a_spec
+  end
+
+  describe "#ready_to_enqueue?" do
+    context "when in enqueued state" do
+      it "is falsey" do
+        spec = described_class.new(dep)
+        spec.state = :enqueued
+        expect(spec.ready_to_enqueue?).to be_falsey
+      end
+    end
+
+    context "when in installed state" do
+      it "returns falsey" do
+        spec = described_class.new(dep)
+        spec.state = :installed
+        expect(spec.ready_to_enqueue?).to be_falsey
+      end
+    end
+
+    it "returns truthy" do
+      spec = described_class.new(dep)
+      expect(spec.ready_to_enqueue?).to be_truthy
+    end
+  end
+
+  describe "#dependencies_installed?" do
+    context "when all dependencies are installed" do
+      it "returns true" do
+        dependencies = []
+        dependencies << instance_double("SpecInstallation", :spec => "alpha", :name => "alpha", :installed? => true, :all_dependencies => [], :type => :production)
+        dependencies << instance_double("SpecInstallation", :spec => "beta", :name => "beta", :installed? => true, :all_dependencies => [], :type => :production)
+        all_specs = dependencies + [instance_double("SpecInstallation", :spec => "gamma", :name => "gamma", :installed? => false, :all_dependencies => [], :type => :production)]
+        spec = described_class.new(dep)
+        allow(spec).to receive(:all_dependencies).and_return(dependencies)
+        expect(spec.dependencies_installed?(all_specs)).to be_truthy
+      end
+    end
+
+    context "when all dependencies are not installed" do
+      it "returns false" do
+        dependencies = []
+        dependencies << instance_double("SpecInstallation", :spec => "alpha", :name => "alpha", :installed? => false, :all_dependencies => [], :type => :production)
+        dependencies << instance_double("SpecInstallation", :spec => "beta", :name => "beta", :installed? => true, :all_dependencies => [], :type => :production)
+        all_specs = dependencies + [instance_double("SpecInstallation", :spec => "gamma", :name => "gamma", :installed? => false, :all_dependencies => [], :type => :production)]
+        spec = described_class.new(dep)
+        allow(spec).to receive(:all_dependencies).and_return(dependencies)
+        expect(spec.dependencies_installed?(all_specs)).to be_falsey
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/lockfile_parser_spec.rb b/spec/bundler/bundler/lockfile_parser_spec.rb
new file mode 100644
index 0000000000..3a6d61336f
--- /dev/null
+++ b/spec/bundler/bundler/lockfile_parser_spec.rb
@@ -0,0 +1,153 @@
+# frozen_string_literal: true
+
+require "bundler/lockfile_parser"
+
+RSpec.describe Bundler::LockfileParser do
+  let(:lockfile_contents) { strip_whitespace(<<-L) }
+    GIT
+      remote: https://github.com/alloy/peiji-san.git
+      revision: eca485d8dc95f12aaec1a434b49d295c7e91844b
+      specs:
+        peiji-san (1.2.0)
+
+    GEM
+      remote: https://rubygems.org/
+      specs:
+        rake (10.3.2)
+
+    PLATFORMS
+      ruby
+
+    DEPENDENCIES
+      peiji-san!
+      rake
+
+    RUBY VERSION
+       ruby 2.1.3p242
+
+    BUNDLED WITH
+       1.12.0.rc.2
+  L
+
+  describe ".sections_in_lockfile" do
+    it "returns the attributes" do
+      attributes = described_class.sections_in_lockfile(lockfile_contents)
+      expect(attributes).to contain_exactly(
+        "BUNDLED WITH", "DEPENDENCIES", "GEM", "GIT", "PLATFORMS", "RUBY VERSION"
+      )
+    end
+  end
+
+  describe ".unknown_sections_in_lockfile" do
+    let(:lockfile_contents) { strip_whitespace(<<-L) }
+      UNKNOWN ATTR
+
+      UNKNOWN ATTR 2
+        random contents
+    L
+
+    it "returns the unknown attributes" do
+      attributes = described_class.unknown_sections_in_lockfile(lockfile_contents)
+      expect(attributes).to contain_exactly("UNKNOWN ATTR", "UNKNOWN ATTR 2")
+    end
+  end
+
+  describe ".sections_to_ignore" do
+    subject { described_class.sections_to_ignore(base_version) }
+
+    context "with a nil base version" do
+      let(:base_version) { nil }
+
+      it "returns the same as > 1.0" do
+        expect(subject).to contain_exactly(
+          described_class::BUNDLED, described_class::RUBY, described_class::PLUGIN
+        )
+      end
+    end
+
+    context "with a prerelease base version" do
+      let(:base_version) { Gem::Version.create("1.11.0.rc.1") }
+
+      it "returns the same as for the release version" do
+        expect(subject).to contain_exactly(
+          described_class::RUBY, described_class::PLUGIN
+        )
+      end
+    end
+
+    context "with a current version" do
+      let(:base_version) { Gem::Version.create(Bundler::VERSION) }
+
+      it "returns an empty array" do
+        expect(subject).to eq([])
+      end
+    end
+
+    context "with a future version" do
+      let(:base_version) { Gem::Version.create("5.5.5") }
+
+      it "returns an empty array" do
+        expect(subject).to eq([])
+      end
+    end
+  end
+
+  describe "#initialize" do
+    before { allow(Bundler::SharedHelpers).to receive(:find_gemfile).and_return(bundled_app("gems.rb")) }
+    subject { described_class.new(lockfile_contents) }
+
+    let(:sources) do
+      [Bundler::Source::Git.new("uri" => "https://github.com/alloy/peiji-san.git", "revision" => "eca485d8dc95f12aaec1a434b49d295c7e91844b"),
+       Bundler::Source::Rubygems.new("remotes" => ["https://rubygems.org"])]
+    end
+    let(:dependencies) do
+      {
+        "peiji-san" => Bundler::Dependency.new("peiji-san", ">= 0"),
+        "rake" => Bundler::Dependency.new("rake", ">= 0"),
+      }
+    end
+    let(:specs) do
+      [
+        Bundler::LazySpecification.new("peiji-san", v("1.2.0"), rb),
+        Bundler::LazySpecification.new("rake", v("10.3.2"), rb),
+      ]
+    end
+    let(:platforms) { [rb] }
+    let(:bundler_version) { Gem::Version.new("1.12.0.rc.2") }
+    let(:ruby_version) { "ruby 2.1.3p242" }
+
+    shared_examples_for "parsing" do
+      it "parses correctly" do
+        expect(subject.sources).to eq sources
+        expect(subject.dependencies).to eq dependencies
+        expect(subject.specs).to eq specs
+        expect(Hash[subject.specs.map {|s| [s, s.dependencies] }]).to eq Hash[subject.specs.map {|s| [s, s.dependencies] }]
+        expect(subject.platforms).to eq platforms
+        expect(subject.bundler_version).to eq bundler_version
+        expect(subject.ruby_version).to eq ruby_version
+      end
+    end
+
+    include_examples "parsing"
+
+    context "when an extra section is at the end" do
+      let(:lockfile_contents) { super() + "\n\nFOO BAR\n  baz\n   baa\n    qux\n" }
+      include_examples "parsing"
+    end
+
+    context "when an extra section is at the start" do
+      let(:lockfile_contents) { "FOO BAR\n  baz\n   baa\n    qux\n\n" + super() }
+      include_examples "parsing"
+    end
+
+    context "when an extra section is in the middle" do
+      let(:lockfile_contents) { super().split(/(?=GEM)/).insert(1, "FOO BAR\n  baz\n   baa\n    qux\n\n").join }
+      include_examples "parsing"
+    end
+
+    context "when a dependency has options" do
+      let(:lockfile_contents) { super().sub("peiji-san!", "peiji-san!\n    foo: bar") }
+      include_examples "parsing"
+    end
+  end
+end
diff --git a/spec/bundler/bundler/mirror_spec.rb b/spec/bundler/bundler/mirror_spec.rb
new file mode 100644
index 0000000000..acd0895f2f
--- /dev/null
+++ b/spec/bundler/bundler/mirror_spec.rb
@@ -0,0 +1,329 @@
+# frozen_string_literal: true
+
+require "bundler/mirror"
+
+RSpec.describe Bundler::Settings::Mirror do
+  let(:mirror) { Bundler::Settings::Mirror.new }
+
+  it "returns zero when fallback_timeout is not set" do
+    expect(mirror.fallback_timeout).to eq(0)
+  end
+
+  it "takes a number as a fallback_timeout" do
+    mirror.fallback_timeout = 1
+    expect(mirror.fallback_timeout).to eq(1)
+  end
+
+  it "takes truthy as a default fallback timeout" do
+    mirror.fallback_timeout = true
+    expect(mirror.fallback_timeout).to eq(0.1)
+  end
+
+  it "takes falsey as a zero fallback timeout" do
+    mirror.fallback_timeout = false
+    expect(mirror.fallback_timeout).to eq(0)
+  end
+
+  it "takes a string with 'true' as a default fallback timeout" do
+    mirror.fallback_timeout = "true"
+    expect(mirror.fallback_timeout).to eq(0.1)
+  end
+
+  it "takes a string with 'false' as a zero fallback timeout" do
+    mirror.fallback_timeout = "false"
+    expect(mirror.fallback_timeout).to eq(0)
+  end
+
+  it "takes a string for the uri but returns an uri object" do
+    mirror.uri = "http://localhost:9292"
+    expect(mirror.uri).to eq(URI("http://localhost:9292"))
+  end
+
+  it "takes an uri object for the uri" do
+    mirror.uri = URI("http://localhost:9293")
+    expect(mirror.uri).to eq(URI("http://localhost:9293"))
+  end
+
+  context "without a uri" do
+    it "invalidates the mirror" do
+      mirror.validate!
+      expect(mirror.valid?).to be_falsey
+    end
+  end
+
+  context "with an uri" do
+    before { mirror.uri = "http://localhost:9292" }
+
+    context "without a fallback timeout" do
+      it "is not valid by default" do
+        expect(mirror.valid?).to be_falsey
+      end
+
+      context "when probed" do
+        let(:probe) { double }
+
+        context "with a replying mirror" do
+          before do
+            allow(probe).to receive(:replies?).and_return(true)
+            mirror.validate!(probe)
+          end
+
+          it "is valid" do
+            expect(mirror.valid?).to be_truthy
+          end
+        end
+
+        context "with a non replying mirror" do
+          before do
+            allow(probe).to receive(:replies?).and_return(false)
+            mirror.validate!(probe)
+          end
+
+          it "is still valid" do
+            expect(mirror.valid?).to be_truthy
+          end
+        end
+      end
+    end
+
+    context "with a fallback timeout" do
+      before { mirror.fallback_timeout = 1 }
+
+      it "is not valid by default" do
+        expect(mirror.valid?).to be_falsey
+      end
+
+      context "when probed" do
+        let(:probe) { double }
+
+        context "with a replying mirror" do
+          before do
+            allow(probe).to receive(:replies?).and_return(true)
+            mirror.validate!(probe)
+          end
+
+          it "is valid" do
+            expect(mirror.valid?).to be_truthy
+          end
+
+          it "is validated only once" do
+            allow(probe).to receive(:replies?).and_raise("Only once!")
+            mirror.validate!(probe)
+            expect(mirror.valid?).to be_truthy
+          end
+        end
+
+        context "with a non replying mirror" do
+          before do
+            allow(probe).to receive(:replies?).and_return(false)
+            mirror.validate!(probe)
+          end
+
+          it "is not valid" do
+            expect(mirror.valid?).to be_falsey
+          end
+
+          it "is validated only once" do
+            allow(probe).to receive(:replies?).and_raise("Only once!")
+            mirror.validate!(probe)
+            expect(mirror.valid?).to be_falsey
+          end
+        end
+      end
+    end
+
+    describe "#==" do
+      it "returns true if uri and fallback timeout are the same" do
+        uri = "https://ruby.taobao.org"
+        mirror = Bundler::Settings::Mirror.new(uri, 1)
+        another_mirror = Bundler::Settings::Mirror.new(uri, 1)
+
+        expect(mirror == another_mirror).to be true
+      end
+    end
+  end
+end
+
+RSpec.describe Bundler::Settings::Mirrors do
+  let(:localhost_uri) { URI("http://localhost:9292") }
+
+  context "with a just created mirror" do
+    let(:mirrors) do
+      probe = double
+      allow(probe).to receive(:replies?).and_return(true)
+      Bundler::Settings::Mirrors.new(probe)
+    end
+
+    it "returns a mirror that contains the source uri for an unknown uri" do
+      mirror = mirrors.for("http://rubygems.org/")
+      expect(mirror).to eq(Bundler::Settings::Mirror.new("http://rubygems.org/"))
+    end
+
+    it "parses a mirror key and returns a mirror for the parsed uri" do
+      mirrors.parse("mirror.http://rubygems.org/", localhost_uri)
+      expect(mirrors.for("http://rubygems.org/").uri).to eq(localhost_uri)
+    end
+
+    it "parses a relative mirror key and returns a mirror for the parsed http uri" do
+      mirrors.parse("mirror.rubygems.org", localhost_uri)
+      expect(mirrors.for("http://rubygems.org/").uri).to eq(localhost_uri)
+    end
+
+    it "parses a relative mirror key and returns a mirror for the parsed https uri" do
+      mirrors.parse("mirror.rubygems.org", localhost_uri)
+      expect(mirrors.for("https://rubygems.org/").uri).to eq(localhost_uri)
+    end
+
+    context "with a uri parsed already" do
+      before { mirrors.parse("mirror.http://rubygems.org/", localhost_uri) }
+
+      it "takes a mirror fallback_timeout and assigns the timeout" do
+        mirrors.parse("mirror.http://rubygems.org.fallback_timeout", "2")
+        expect(mirrors.for("http://rubygems.org/").fallback_timeout).to eq(2)
+      end
+
+      it "parses a 'true' fallback timeout and sets the default timeout" do
+        mirrors.parse("mirror.http://rubygems.org.fallback_timeout", "true")
+        expect(mirrors.for("http://rubygems.org/").fallback_timeout).to eq(0.1)
+      end
+
+      it "parses a 'false' fallback timeout and sets it to zero" do
+        mirrors.parse("mirror.http://rubygems.org.fallback_timeout", "false")
+        expect(mirrors.for("http://rubygems.org/").fallback_timeout).to eq(0)
+      end
+    end
+  end
+
+  context "with a mirror prober that replies on time" do
+    let(:mirrors) do
+      probe = double
+      allow(probe).to receive(:replies?).and_return(true)
+      Bundler::Settings::Mirrors.new(probe)
+    end
+
+    context "with a default fallback_timeout for rubygems.org" do
+      before do
+        mirrors.parse("mirror.http://rubygems.org/", localhost_uri)
+        mirrors.parse("mirror.http://rubygems.org.fallback_timeout", "true")
+      end
+
+      it "returns localhost" do
+        expect(mirrors.for("http://rubygems.org").uri).to eq(localhost_uri)
+      end
+    end
+
+    context "with a mirror for all" do
+      before do
+        mirrors.parse("mirror.all", localhost_uri)
+      end
+
+      context "without a fallback timeout" do
+        it "returns localhost uri for rubygems" do
+          expect(mirrors.for("http://rubygems.org").uri).to eq(localhost_uri)
+        end
+
+        it "returns localhost for any other url" do
+          expect(mirrors.for("http://whatever.com/").uri).to eq(localhost_uri)
+        end
+      end
+      context "with a fallback timeout" do
+        before { mirrors.parse("mirror.all.fallback_timeout", "1") }
+
+        it "returns localhost uri for rubygems" do
+          expect(mirrors.for("http://rubygems.org").uri).to eq(localhost_uri)
+        end
+
+        it "returns localhost for any other url" do
+          expect(mirrors.for("http://whatever.com/").uri).to eq(localhost_uri)
+        end
+      end
+    end
+  end
+
+  context "with a mirror prober that does not reply on time" do
+    let(:mirrors) do
+      probe = double
+      allow(probe).to receive(:replies?).and_return(false)
+      Bundler::Settings::Mirrors.new(probe)
+    end
+
+    context "with a localhost mirror for all" do
+      before { mirrors.parse("mirror.all", localhost_uri) }
+
+      context "without a fallback timeout" do
+        it "returns localhost" do
+          expect(mirrors.for("http://whatever.com").uri).to eq(localhost_uri)
+        end
+      end
+
+      context "with a fallback timeout" do
+        before { mirrors.parse("mirror.all.fallback_timeout", "true") }
+
+        it "returns the source uri, not localhost" do
+          expect(mirrors.for("http://whatever.com").uri).to eq(URI("http://whatever.com/"))
+        end
+      end
+    end
+
+    context "with localhost as a mirror for rubygems.org" do
+      before { mirrors.parse("mirror.http://rubygems.org/", localhost_uri) }
+
+      context "without a fallback timeout" do
+        it "returns the uri that is not mirrored" do
+          expect(mirrors.for("http://whatever.com").uri).to eq(URI("http://whatever.com/"))
+        end
+
+        it "returns localhost for rubygems.org" do
+          expect(mirrors.for("http://rubygems.org/").uri).to eq(localhost_uri)
+        end
+      end
+
+      context "with a fallback timeout" do
+        before { mirrors.parse("mirror.http://rubygems.org/.fallback_timeout", "true") }
+
+        it "returns the uri that is not mirrored" do
+          expect(mirrors.for("http://whatever.com").uri).to eq(URI("http://whatever.com/"))
+        end
+
+        it "returns rubygems.org for rubygems.org" do
+          expect(mirrors.for("http://rubygems.org/").uri).to eq(URI("http://rubygems.org/"))
+        end
+      end
+    end
+  end
+end
+
+RSpec.describe Bundler::Settings::TCPSocketProbe do
+  let(:probe) { Bundler::Settings::TCPSocketProbe.new }
+
+  context "with a listening TCP Server" do
+    def with_server_and_mirror
+      server = TCPServer.new("127.0.0.1", 0)
+      mirror = Bundler::Settings::Mirror.new("http://localhost:#{server.addr[1]}", 1)
+      yield server, mirror
+      server.close unless server.closed?
+    end
+
+    it "probes the server correctly", :ruby_repo do
+      with_server_and_mirror do |server, mirror|
+        expect(server.closed?).to be_falsey
+        expect(probe.replies?(mirror)).to be_truthy
+      end
+    end
+
+    it "probes falsey when the server is down" do
+      with_server_and_mirror do |server, mirror|
+        server.close
+        expect(probe.replies?(mirror)).to be_falsey
+      end
+    end
+  end
+
+  context "with an invalid mirror" do
+    let(:mirror) { Bundler::Settings::Mirror.new("http://127.0.0.127:9292", true) }
+
+    it "fails with a timeout when there is nothing to tcp handshake" do
+      expect(probe.replies?(mirror)).to be_falsey
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/api/source_spec.rb b/spec/bundler/bundler/plugin/api/source_spec.rb
new file mode 100644
index 0000000000..2c50ff56a4
--- /dev/null
+++ b/spec/bundler/bundler/plugin/api/source_spec.rb
@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::API::Source do
+  let(:uri) { "uri://to/test" }
+  let(:type) { "spec_type" }
+
+  subject(:source) do
+    klass = Class.new
+    klass.send :include, Bundler::Plugin::API::Source
+    klass.new("uri" => uri, "type" => type)
+  end
+
+  describe "attributes" do
+    it "allows access to uri" do
+      expect(source.uri).to eq("uri://to/test")
+    end
+
+    it "allows access to name" do
+      expect(source.name).to eq("spec_type at uri://to/test")
+    end
+  end
+
+  context "post_install" do
+    let(:installer) { double(:installer) }
+
+    before do
+      allow(Bundler::Source::Path::Installer).to receive(:new) { installer }
+    end
+
+    it "calls Path::Installer's post_install" do
+      expect(installer).to receive(:post_install).once
+
+      source.post_install(double(:spec))
+    end
+  end
+
+  context "install_path" do
+    let(:uri) { "uri://to/a/repository-name" }
+    let(:hash) { Digest(:SHA1).hexdigest(uri) }
+    let(:install_path) { Pathname.new "/bundler/install/path" }
+
+    before do
+      allow(Bundler).to receive(:install_path) { install_path }
+    end
+
+    it "returns basename with uri_hash" do
+      expected = Pathname.new "#{install_path}/repository-name-#{hash[0..11]}"
+      expect(source.install_path).to eq(expected)
+    end
+  end
+
+  context "to_lock" do
+    it "returns the string with remote and type" do
+      expected = strip_whitespace <<-L
+        PLUGIN SOURCE
+          remote: #{uri}
+          type: #{type}
+          specs:
+      L
+
+      expect(source.to_lock).to eq(expected)
+    end
+
+    context "with additional options to lock" do
+      before do
+        allow(source).to receive(:options_to_lock) { { "first" => "option" } }
+      end
+
+      it "includes them" do
+        expected = strip_whitespace <<-L
+          PLUGIN SOURCE
+            remote: #{uri}
+            type: #{type}
+            first: option
+            specs:
+        L
+
+        expect(source.to_lock).to eq(expected)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/api_spec.rb b/spec/bundler/bundler/plugin/api_spec.rb
new file mode 100644
index 0000000000..58fb908572
--- /dev/null
+++ b/spec/bundler/bundler/plugin/api_spec.rb
@@ -0,0 +1,83 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::API do
+  context "plugin declarations" do
+    before do
+      stub_const "UserPluginClass", Class.new(Bundler::Plugin::API)
+    end
+
+    describe "#command" do
+      it "declares a command plugin with same class as handler" do
+        expect(Bundler::Plugin).
+          to receive(:add_command).with("meh", UserPluginClass).once
+
+        UserPluginClass.command "meh"
+      end
+
+      it "accepts another class as argument that handles the command" do
+        stub_const "NewClass", Class.new
+        expect(Bundler::Plugin).to receive(:add_command).with("meh", NewClass).once
+
+        UserPluginClass.command "meh", NewClass
+      end
+    end
+
+    describe "#source" do
+      it "declares a source plugin with same class as handler" do
+        expect(Bundler::Plugin).
+          to receive(:add_source).with("a_source", UserPluginClass).once
+
+        UserPluginClass.source "a_source"
+      end
+
+      it "accepts another class as argument that handles the command" do
+        stub_const "NewClass", Class.new
+        expect(Bundler::Plugin).to receive(:add_source).with("a_source", NewClass).once
+
+        UserPluginClass.source "a_source", NewClass
+      end
+    end
+
+    describe "#hook" do
+      it "accepts a block and passes it to Plugin module" do
+        foo = double("tester")
+        expect(foo).to receive(:called)
+
+        expect(Bundler::Plugin).to receive(:add_hook).with("post-foo").and_yield
+
+        Bundler::Plugin::API.hook("post-foo") { foo.called }
+      end
+    end
+  end
+
+  context "bundler interfaces provided" do
+    before do
+      stub_const "UserPluginClass", Class.new(Bundler::Plugin::API)
+    end
+
+    subject(:api) { UserPluginClass.new }
+
+    # A test of delegation
+    it "provides the Bundler's functions" do
+      expect(Bundler).to receive(:an_unknown_function).once
+
+      api.an_unknown_function
+    end
+
+    it "includes Bundler::SharedHelpers' functions" do
+      expect(Bundler::SharedHelpers).to receive(:an_unknown_helper).once
+
+      api.an_unknown_helper
+    end
+
+    context "#tmp" do
+      it "provides a tmp dir" do
+        expect(api.tmp("mytmp")).to be_directory
+      end
+
+      it "accepts multiple names for suffix" do
+        expect(api.tmp("myplugin", "download")).to be_directory
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/dsl_spec.rb b/spec/bundler/bundler/plugin/dsl_spec.rb
new file mode 100644
index 0000000000..be23db3bba
--- /dev/null
+++ b/spec/bundler/bundler/plugin/dsl_spec.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::DSL do
+  DSL = Bundler::Plugin::DSL
+
+  subject(:dsl) { Bundler::Plugin::DSL.new }
+
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new "/" }
+  end
+
+  describe "it ignores only the methods defined in Bundler::Dsl" do
+    it "doesn't raises error for Dsl methods" do
+      expect { dsl.install_if }.not_to raise_error
+    end
+
+    it "raises error for other methods" do
+      expect { dsl.no_method }.to raise_error(DSL::PluginGemfileError)
+    end
+  end
+
+  describe "source block" do
+    it "adds #source with :type to list and also inferred_plugins list" do
+      expect(dsl).to receive(:plugin).with("bundler-source-news").once
+
+      dsl.source("some_random_url", :type => "news") {}
+
+      expect(dsl.inferred_plugins).to eq(["bundler-source-news"])
+    end
+
+    it "registers a source type plugin only once for multiple declataions" do
+      expect(dsl).to receive(:plugin).with("bundler-source-news").and_call_original.once
+
+      dsl.source("some_random_url", :type => "news") {}
+      dsl.source("another_random_url", :type => "news") {}
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/events_spec.rb b/spec/bundler/bundler/plugin/events_spec.rb
new file mode 100644
index 0000000000..b09e915682
--- /dev/null
+++ b/spec/bundler/bundler/plugin/events_spec.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::Events do
+  context "plugin events" do
+    describe "#define" do
+      it "raises when redefining a constant" do
+        expect do
+          Bundler::Plugin::Events.send(:define, :GEM_BEFORE_INSTALL_ALL, "another-value")
+        end.to raise_error(ArgumentError)
+      end
+
+      it "can define a new constant" do
+        Bundler::Plugin::Events.send(:define, :NEW_CONSTANT, "value")
+        expect(Bundler::Plugin::Events::NEW_CONSTANT).to eq("value")
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/index_spec.rb b/spec/bundler/bundler/plugin/index_spec.rb
new file mode 100644
index 0000000000..ca3476ea2a
--- /dev/null
+++ b/spec/bundler/bundler/plugin/index_spec.rb
@@ -0,0 +1,186 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::Index do
+  Index = Bundler::Plugin::Index
+
+  before do
+    gemfile ""
+    path = lib_path(plugin_name)
+    index.register_plugin("new-plugin", path.to_s, [path.join("lib").to_s], commands, sources, hooks)
+  end
+
+  let(:plugin_name) { "new-plugin" }
+  let(:commands) { [] }
+  let(:sources) { [] }
+  let(:hooks) { [] }
+
+  subject(:index) { Index.new }
+
+  describe "#register plugin" do
+    it "is available for retrieval" do
+      expect(index.plugin_path(plugin_name)).to eq(lib_path(plugin_name))
+    end
+
+    it "load_paths is available for retrival" do
+      expect(index.load_paths(plugin_name)).to eq([lib_path(plugin_name).join("lib").to_s])
+    end
+
+    it "is persistent" do
+      new_index = Index.new
+      expect(new_index.plugin_path(plugin_name)).to eq(lib_path(plugin_name))
+    end
+
+    it "load_paths are persistent" do
+      new_index = Index.new
+      expect(new_index.load_paths(plugin_name)).to eq([lib_path(plugin_name).join("lib").to_s])
+    end
+  end
+
+  describe "commands" do
+    let(:commands) { ["newco"] }
+
+    it "returns the plugins name on query" do
+      expect(index.command_plugin("newco")).to eq(plugin_name)
+    end
+
+    it "raises error on conflict" do
+      expect do
+        index.register_plugin("aplugin", lib_path("aplugin").to_s, lib_path("aplugin").join("lib").to_s, ["newco"], [], [])
+      end.to raise_error(Index::CommandConflict)
+    end
+
+    it "is persistent" do
+      new_index = Index.new
+      expect(new_index.command_plugin("newco")).to eq(plugin_name)
+    end
+  end
+
+  describe "source" do
+    let(:sources) { ["new_source"] }
+
+    it "returns the plugins name on query" do
+      expect(index.source_plugin("new_source")).to eq(plugin_name)
+    end
+
+    it "raises error on conflict" do
+      expect do
+        index.register_plugin("aplugin", lib_path("aplugin").to_s, lib_path("aplugin").join("lib").to_s, [], ["new_source"], [])
+      end.to raise_error(Index::SourceConflict)
+    end
+
+    it "is persistent" do
+      new_index = Index.new
+      expect(new_index.source_plugin("new_source")).to eq(plugin_name)
+    end
+  end
+
+  describe "hook" do
+    let(:hooks) { ["after-bar"] }
+
+    it "returns the plugins name on query" do
+      expect(index.hook_plugins("after-bar")).to include(plugin_name)
+    end
+
+    it "is persistent" do
+      new_index = Index.new
+      expect(new_index.hook_plugins("after-bar")).to eq([plugin_name])
+    end
+
+    context "that are not registered", :focused do
+      let(:file) { double("index-file") }
+
+      before do
+        index.hook_plugins("not-there")
+        allow(File).to receive(:open).and_yield(file)
+      end
+
+      it "should not save it with next registered hook" do
+        expect(file).to receive(:puts) do |content|
+          expect(content).not_to include("not-there")
+        end
+
+        index.register_plugin("aplugin", lib_path("aplugin").to_s, lib_path("aplugin").join("lib").to_s, [], [], [])
+      end
+    end
+  end
+
+  describe "global index" do
+    before do
+      Dir.chdir(tmp) do
+        Bundler::Plugin.reset!
+        path = lib_path("gplugin")
+        index.register_plugin("gplugin", path.to_s, [path.join("lib").to_s], [], ["glb_source"], [])
+      end
+    end
+
+    it "skips sources" do
+      new_index = Index.new
+      expect(new_index.source_plugin("glb_source")).to be_falsy
+    end
+  end
+
+  describe "after conflict" do
+    let(:commands) { ["foo"] }
+    let(:sources) { ["bar"] }
+    let(:hooks) { ["hoook"] }
+
+    shared_examples "it cleans up" do
+      it "the path" do
+        expect(index.installed?("cplugin")).to be_falsy
+      end
+
+      it "the command" do
+        expect(index.command_plugin("xfoo")).to be_falsy
+      end
+
+      it "the source" do
+        expect(index.source_plugin("xbar")).to be_falsy
+      end
+
+      it "the hook" do
+        expect(index.hook_plugins("xhoook")).to be_empty
+      end
+    end
+
+    context "on command conflict it cleans up" do
+      before do
+        expect do
+          path = lib_path("cplugin")
+          index.register_plugin("cplugin", path.to_s, [path.join("lib").to_s], ["foo"], ["xbar"], ["xhoook"])
+        end.to raise_error(Index::CommandConflict)
+      end
+
+      include_examples "it cleans up"
+    end
+
+    context "on source conflict it cleans up" do
+      before do
+        expect do
+          path = lib_path("cplugin")
+          index.register_plugin("cplugin", path.to_s, [path.join("lib").to_s], ["xfoo"], ["bar"], ["xhoook"])
+        end.to raise_error(Index::SourceConflict)
+      end
+
+      include_examples "it cleans up"
+    end
+
+    context "on command and source conflict it cleans up" do
+      before do
+        expect do
+          path = lib_path("cplugin")
+          index.register_plugin("cplugin", path.to_s, [path.join("lib").to_s], ["foo"], ["bar"], ["xhoook"])
+        end.to raise_error(Index::CommandConflict)
+      end
+
+      include_examples "it cleans up"
+    end
+  end
+
+  describe "readonly disk without home" do
+    it "ignores being unable to create temp home dir" do
+      expect_any_instance_of(Bundler::Plugin::Index).to receive(:global_index_file).
+        and_raise(Bundler::GenericSystemCallError.new("foo", "bar"))
+      Bundler::Plugin::Index.new
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/installer_spec.rb b/spec/bundler/bundler/plugin/installer_spec.rb
new file mode 100644
index 0000000000..f8bf8450c9
--- /dev/null
+++ b/spec/bundler/bundler/plugin/installer_spec.rb
@@ -0,0 +1,104 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::Installer do
+  subject(:installer) { Bundler::Plugin::Installer.new }
+
+  before do
+    # allow(Bundler::SharedHelpers).to receive(:find_gemfile).and_return(Pathname.new("/Gemfile"))
+  end
+
+  describe "cli install" do
+    it "uses Gem.sources when non of the source is provided" do
+      sources = double(:sources)
+      Bundler.settings # initialize it before we have to touch rubygems.ext_lock
+      allow(Bundler).to receive_message_chain("rubygems.sources") { sources }
+
+      allow(installer).to receive(:install_rubygems).
+        with("new-plugin", [">= 0"], sources).once
+
+      installer.install("new-plugin", {})
+    end
+
+    describe "with mocked installers" do
+      let(:spec) { double(:spec) }
+      it "returns the installed spec after installing git plugins" do
+        allow(installer).to receive(:install_git).
+          and_return("new-plugin" => spec)
+
+        expect(installer.install(["new-plugin"], :git => "https://some.ran/dom")).
+          to eq("new-plugin" => spec)
+      end
+
+      it "returns the installed spec after installing rubygems plugins" do
+        allow(installer).to receive(:install_rubygems).
+          and_return("new-plugin" => spec)
+
+        expect(installer.install(["new-plugin"], :source => "https://some.ran/dom")).
+          to eq("new-plugin" => spec)
+      end
+    end
+
+    describe "with actual installers" do
+      before do
+        build_repo2 do
+          build_plugin "re-plugin"
+          build_plugin "ma-plugin"
+        end
+      end
+
+      context "git plugins" do
+        before do
+          build_git "ga-plugin", :path => lib_path("ga-plugin") do |s|
+            s.write "plugins.rb"
+          end
+        end
+
+        let(:result) do
+          installer.install(["ga-plugin"], :git => "file://#{lib_path("ga-plugin")}")
+        end
+
+        it "returns the installed spec after installing" do
+          spec = result["ga-plugin"]
+          expect(spec.full_name).to eq "ga-plugin-1.0"
+        end
+
+        it "has expected full gem path" do
+          rev = revision_for(lib_path("ga-plugin"))
+          expect(result["ga-plugin"].full_gem_path).
+            to eq(Bundler::Plugin.root.join("bundler", "gems", "ga-plugin-#{rev[0..11]}").to_s)
+        end
+      end
+
+      context "rubygems plugins" do
+        let(:result) do
+          installer.install(["re-plugin"], :source => "file://#{gem_repo2}")
+        end
+
+        it "returns the installed spec after installing " do
+          expect(result["re-plugin"]).to be_kind_of(Bundler::RemoteSpecification)
+        end
+
+        it "has expected full_gem)path" do
+          expect(result["re-plugin"].full_gem_path).
+            to eq(global_plugin_gem("re-plugin-1.0").to_s)
+        end
+      end
+
+      context "multiple plugins" do
+        let(:result) do
+          installer.install(["re-plugin", "ma-plugin"], :source => "file://#{gem_repo2}")
+        end
+
+        it "returns the installed spec after installing " do
+          expect(result["re-plugin"]).to be_kind_of(Bundler::RemoteSpecification)
+          expect(result["ma-plugin"]).to be_kind_of(Bundler::RemoteSpecification)
+        end
+
+        it "has expected full_gem)path" do
+          expect(result["re-plugin"].full_gem_path).to eq(global_plugin_gem("re-plugin-1.0").to_s)
+          expect(result["ma-plugin"].full_gem_path).to eq(global_plugin_gem("ma-plugin-1.0").to_s)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin/source_list_spec.rb b/spec/bundler/bundler/plugin/source_list_spec.rb
new file mode 100644
index 0000000000..64a1233dd1
--- /dev/null
+++ b/spec/bundler/bundler/plugin/source_list_spec.rb
@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin::SourceList do
+  SourceList = Bundler::Plugin::SourceList
+
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new "/" }
+  end
+
+  subject(:source_list) { SourceList.new }
+
+  describe "adding sources uses classes for plugin" do
+    it "uses Plugin::Installer::Rubygems for rubygems sources" do
+      source = source_list.
+        add_rubygems_source("remotes" => ["https://existing-rubygems.org"])
+      expect(source).to be_instance_of(Bundler::Plugin::Installer::Rubygems)
+    end
+
+    it "uses Plugin::Installer::Git for git sources" do
+      source = source_list.
+        add_git_source("uri" => "git://existing-git.org/path.git")
+      expect(source).to be_instance_of(Bundler::Plugin::Installer::Git)
+    end
+  end
+end
diff --git a/spec/bundler/bundler/plugin_spec.rb b/spec/bundler/bundler/plugin_spec.rb
new file mode 100644
index 0000000000..9266fad1eb
--- /dev/null
+++ b/spec/bundler/bundler/plugin_spec.rb
@@ -0,0 +1,309 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Plugin do
+  Plugin = Bundler::Plugin
+
+  let(:installer) { double(:installer) }
+  let(:index) { double(:index) }
+  let(:spec) { double(:spec) }
+  let(:spec2) { double(:spec2) }
+
+  before do
+    build_lib "new-plugin", :path => lib_path("new-plugin") do |s|
+      s.write "plugins.rb"
+    end
+
+    build_lib "another-plugin", :path => lib_path("another-plugin") do |s|
+      s.write "plugins.rb"
+    end
+
+    allow(spec).to receive(:full_gem_path).
+      and_return(lib_path("new-plugin").to_s)
+    allow(spec).to receive(:load_paths).
+      and_return([lib_path("new-plugin").join("lib").to_s])
+
+    allow(spec2).to receive(:full_gem_path).
+      and_return(lib_path("another-plugin").to_s)
+    allow(spec2).to receive(:load_paths).
+      and_return([lib_path("another-plugin").join("lib").to_s])
+
+    allow(Plugin::Installer).to receive(:new) { installer }
+    allow(Plugin).to receive(:index) { index }
+    allow(index).to receive(:register_plugin)
+  end
+
+  describe "install command" do
+    let(:opts) { { "version" => "~> 1.0", "source" => "foo" } }
+
+    before do
+      allow(installer).to receive(:install).with(["new-plugin"], opts) do
+        { "new-plugin" => spec }
+      end
+    end
+
+    it "passes the name and options to installer" do
+      allow(installer).to receive(:install).with(["new-plugin"], opts) do
+        { "new-plugin" => spec }
+      end.once
+
+      subject.install ["new-plugin"], opts
+    end
+
+    it "validates the installed plugin" do
+      allow(subject).
+        to receive(:validate_plugin!).with(lib_path("new-plugin")).once
+
+      subject.install ["new-plugin"], opts
+    end
+
+    it "registers the plugin with index" do
+      allow(index).to receive(:register_plugin).
+        with("new-plugin", lib_path("new-plugin").to_s, [lib_path("new-plugin").join("lib").to_s], []).once
+      subject.install ["new-plugin"], opts
+    end
+
+    context "multiple plugins" do
+      it do
+        allow(installer).to receive(:install).
+          with(["new-plugin", "another-plugin"], opts) do
+          {
+            "new-plugin" => spec,
+            "another-plugin" => spec2,
+          }
+        end.once
+
+        allow(subject).to receive(:validate_plugin!).twice
+        allow(index).to receive(:register_plugin).twice
+        subject.install ["new-plugin", "another-plugin"], opts
+      end
+    end
+  end
+
+  describe "evaluate gemfile for plugins" do
+    let(:definition) { double("definition") }
+    let(:builder) { double("builder") }
+    let(:gemfile) { bundled_app("Gemfile") }
+
+    before do
+      allow(Plugin::DSL).to receive(:new) { builder }
+      allow(builder).to receive(:eval_gemfile).with(gemfile)
+      allow(builder).to receive(:to_definition) { definition }
+      allow(builder).to receive(:inferred_plugins) { [] }
+    end
+
+    it "doesn't calls installer without any plugins" do
+      allow(definition).to receive(:dependencies) { [] }
+      allow(installer).to receive(:install_definition).never
+
+      subject.gemfile_install(gemfile)
+    end
+
+    context "with dependencies" do
+      let(:plugin_specs) do
+        {
+          "new-plugin" => spec,
+          "another-plugin" => spec2,
+        }
+      end
+
+      before do
+        allow(index).to receive(:installed?) { nil }
+        allow(definition).to receive(:dependencies) { [Bundler::Dependency.new("new-plugin", ">=0"), Bundler::Dependency.new("another-plugin", ">=0")] }
+        allow(installer).to receive(:install_definition) { plugin_specs }
+      end
+
+      it "should validate and register the plugins" do
+        expect(subject).to receive(:validate_plugin!).twice
+        expect(subject).to receive(:register_plugin).twice
+
+        subject.gemfile_install(gemfile)
+      end
+
+      it "should pass the optional plugins to #register_plugin" do
+        allow(builder).to receive(:inferred_plugins) { ["another-plugin"] }
+
+        expect(subject).to receive(:register_plugin).
+          with("new-plugin", spec, false).once
+
+        expect(subject).to receive(:register_plugin).
+          with("another-plugin", spec2, true).once
+
+        subject.gemfile_install(gemfile)
+      end
+    end
+  end
+
+  describe "#command?" do
+    it "returns true value for commands in index" do
+      allow(index).
+        to receive(:command_plugin).with("newcommand") { "my-plugin" }
+      result = subject.command? "newcommand"
+      expect(result).to be_truthy
+    end
+
+    it "returns false value for commands not in index" do
+      allow(index).to receive(:command_plugin).with("newcommand") { nil }
+      result = subject.command? "newcommand"
+      expect(result).to be_falsy
+    end
+  end
+
+  describe "#exec_command" do
+    it "raises UndefinedCommandError when command is not found" do
+      allow(index).to receive(:command_plugin).with("newcommand") { nil }
+      expect { subject.exec_command("newcommand", []) }.
+        to raise_error(Plugin::UndefinedCommandError)
+    end
+  end
+
+  describe "#source?" do
+    it "returns true value for sources in index" do
+      allow(index).
+        to receive(:command_plugin).with("foo-source") { "my-plugin" }
+      result = subject.command? "foo-source"
+      expect(result).to be_truthy
+    end
+
+    it "returns false value for source not in index" do
+      allow(index).to receive(:command_plugin).with("foo-source") { nil }
+      result = subject.command? "foo-source"
+      expect(result).to be_falsy
+    end
+  end
+
+  describe "#source" do
+    it "raises UnknownSourceError when source is not found" do
+      allow(index).to receive(:source_plugin).with("bar") { nil }
+      expect { subject.source("bar") }.
+        to raise_error(Plugin::UnknownSourceError)
+    end
+
+    it "loads the plugin, if not loaded" do
+      allow(index).to receive(:source_plugin).with("foo-bar") { "plugin_name" }
+
+      expect(subject).to receive(:load_plugin).with("plugin_name")
+      subject.source("foo-bar")
+    end
+
+    it "returns the class registered with #add_source" do
+      allow(index).to receive(:source_plugin).with("foo") { "plugin_name" }
+      stub_const "NewClass", Class.new
+
+      subject.add_source("foo", NewClass)
+      expect(subject.source("foo")).to be(NewClass)
+    end
+  end
+
+  describe "#source_from_lock" do
+    it "returns instance of registered class initialized with locked opts" do
+      opts = { "type" => "l_source", "remote" => "xyz", "other" => "random" }
+      allow(index).to receive(:source_plugin).with("l_source") { "plugin_name" }
+
+      stub_const "SClass", Class.new
+      s_instance = double(:s_instance)
+      subject.add_source("l_source", SClass)
+
+      expect(SClass).to receive(:new).
+        with(hash_including("type" => "l_source", "uri" => "xyz", "other" => "random")) { s_instance }
+      expect(subject.source_from_lock(opts)).to be(s_instance)
+    end
+  end
+
+  describe "#root" do
+    context "in app dir" do
+      before do
+        gemfile ""
+      end
+
+      it "returns plugin dir in app .bundle path" do
+        expect(subject.root).to eq(bundled_app.join(".bundle/plugin"))
+      end
+    end
+
+    context "outside app dir" do
+      it "returns plugin dir in global bundle path" do
+        Dir.chdir tmp
+        expect(subject.root).to eq(home.join(".bundle/plugin"))
+      end
+    end
+  end
+
+  describe "#add_hook" do
+    it "raises an ArgumentError on an unregistered event" do
+      ran = false
+      expect do
+        Plugin.add_hook("unregistered-hook") { ran = true }
+      end.to raise_error(ArgumentError)
+      expect(ran).to be(false)
+    end
+  end
+
+  describe "#hook" do
+    before do
+      path = lib_path("foo-plugin")
+      build_lib "foo-plugin", :path => path do |s|
+        s.write "plugins.rb", code
+      end
+
+      Bundler::Plugin::Events.send(:reset)
+      Bundler::Plugin::Events.send(:define, :EVENT_1, "event-1")
+      Bundler::Plugin::Events.send(:define, :EVENT_2, "event-2")
+
+      allow(index).to receive(:hook_plugins).with(Bundler::Plugin::Events::EVENT_1).
+        and_return(["foo-plugin"])
+      allow(index).to receive(:hook_plugins).with(Bundler::Plugin::Events::EVENT_2).
+        and_return(["foo-plugin"])
+      allow(index).to receive(:plugin_path).with("foo-plugin").and_return(path)
+      allow(index).to receive(:load_paths).with("foo-plugin").and_return([])
+    end
+
+    let(:code) { <<-RUBY }
+      Bundler::Plugin::API.hook("event-1") { puts "hook for event 1" }
+    RUBY
+
+    it "raises an ArgumentError on an unregistered event" do
+      expect do
+        Plugin.hook("unregistered-hook")
+      end.to raise_error(ArgumentError)
+    end
+
+    it "executes the hook" do
+      out = capture(:stdout) do
+        Plugin.hook(Bundler::Plugin::Events::EVENT_1)
+      end.strip
+
+      expect(out).to eq("hook for event 1")
+    end
+
+    context "single plugin declaring more than one hook" do
+      let(:code) { <<-RUBY }
+        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT_1) {}
+        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT_2) {}
+        puts "loaded"
+      RUBY
+
+      it "evals plugins.rb once" do
+        out = capture(:stdout) do
+          Plugin.hook(Bundler::Plugin::Events::EVENT_1)
+          Plugin.hook(Bundler::Plugin::Events::EVENT_2)
+        end.strip
+
+        expect(out).to eq("loaded")
+      end
+    end
+
+    context "a block is passed" do
+      let(:code) { <<-RUBY }
+        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT_1) { |&blk| blk.call }
+      RUBY
+
+      it "is passed to the hook" do
+        out = capture(:stdout) do
+          Plugin.hook(Bundler::Plugin::Events::EVENT_1) { puts "win" }
+        end.strip
+
+        expect(out).to eq("win")
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/psyched_yaml_spec.rb b/spec/bundler/bundler/psyched_yaml_spec.rb
new file mode 100644
index 0000000000..d5d68c5cc3
--- /dev/null
+++ b/spec/bundler/bundler/psyched_yaml_spec.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require "bundler/psyched_yaml"
+
+RSpec.describe "Bundler::YamlLibrarySyntaxError" do
+  it "is raised on YAML parse errors" do
+    expect { YAML.parse "{foo" }.to raise_error(Bundler::YamlLibrarySyntaxError)
+  end
+end
diff --git a/spec/bundler/bundler/remote_specification_spec.rb b/spec/bundler/bundler/remote_specification_spec.rb
new file mode 100644
index 0000000000..8115e026d8
--- /dev/null
+++ b/spec/bundler/bundler/remote_specification_spec.rb
@@ -0,0 +1,187 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::RemoteSpecification do
+  let(:name)         { "foo" }
+  let(:version)      { Gem::Version.new("1.0.0") }
+  let(:platform)     { Gem::Platform::RUBY }
+  let(:spec_fetcher) { double(:spec_fetcher) }
+
+  subject { described_class.new(name, version, platform, spec_fetcher) }
+
+  it "is Comparable" do
+    expect(described_class.ancestors).to include(Comparable)
+  end
+
+  it "can match platforms" do
+    expect(described_class.ancestors).to include(Bundler::MatchPlatform)
+  end
+
+  describe "#fetch_platform" do
+    let(:remote_spec) { double(:remote_spec, :platform => "jruby") }
+
+    before { allow(spec_fetcher).to receive(:fetch_spec).and_return(remote_spec) }
+
+    it "should return the spec platform" do
+      expect(subject.fetch_platform).to eq("jruby")
+    end
+  end
+
+  describe "#full_name" do
+    context "when platform is ruby" do
+      it "should return the spec name and version" do
+        expect(subject.full_name).to eq("foo-1.0.0")
+      end
+    end
+
+    context "when platform is nil" do
+      let(:platform) { nil }
+
+      it "should return the spec name and version" do
+        expect(subject.full_name).to eq("foo-1.0.0")
+      end
+    end
+
+    context "when platform is a non-ruby platform" do
+      let(:platform) { "jruby" }
+
+      it "should return the spec name, version, and platform" do
+        expect(subject.full_name).to eq("foo-1.0.0-jruby")
+      end
+    end
+  end
+
+  describe "#<=>" do
+    let(:other_name)         { name }
+    let(:other_version)      { version }
+    let(:other_platform)     { platform }
+    let(:other_spec_fetcher) { spec_fetcher }
+
+    shared_examples_for "a comparison" do
+      context "which exactly matches" do
+        it "returns 0" do
+          expect(subject <=> other).to eq(0)
+        end
+      end
+
+      context "which is different by name" do
+        let(:other_name) { "a" }
+        it "returns 1" do
+          expect(subject <=> other).to eq(1)
+        end
+      end
+
+      context "which has a lower version" do
+        let(:other_version) { Gem::Version.new("0.9.0") }
+        it "returns 1" do
+          expect(subject <=> other).to eq(1)
+        end
+      end
+
+      context "which has a higher version" do
+        let(:other_version) { Gem::Version.new("1.1.0") }
+        it "returns -1" do
+          expect(subject <=> other).to eq(-1)
+        end
+      end
+
+      context "which has a different platform" do
+        let(:other_platform) { Gem::Platform.new("x86-mswin32") }
+        it "returns -1" do
+          expect(subject <=> other).to eq(-1)
+        end
+      end
+    end
+
+    context "comparing another Bundler::RemoteSpecification" do
+      let(:other) do
+        Bundler::RemoteSpecification.new(other_name, other_version,
+          other_platform, nil)
+      end
+
+      it_should_behave_like "a comparison"
+    end
+
+    context "comparing a Gem::Specification" do
+      let(:other) do
+        Gem::Specification.new(other_name, other_version).tap do |s|
+          s.platform = other_platform
+        end
+      end
+
+      it_should_behave_like "a comparison"
+    end
+
+    context "comparing a non sortable object" do
+      let(:other) { Object.new }
+      let(:remote_spec) { double(:remote_spec, :platform => "jruby") }
+
+      before do
+        allow(spec_fetcher).to receive(:fetch_spec).and_return(remote_spec)
+        allow(remote_spec).to receive(:<=>).and_return(nil)
+      end
+
+      it "should use default object comparison" do
+        expect(subject <=> other).to eq(nil)
+      end
+    end
+  end
+
+  describe "#__swap__" do
+    let(:spec) { double(:spec, :dependencies => []) }
+    let(:new_spec) { double(:new_spec, :dependencies => [], :runtime_dependencies => []) }
+
+    before { subject.instance_variable_set(:@_remote_specification, spec) }
+
+    it "should replace remote specification with the passed spec" do
+      expect(subject.instance_variable_get(:@_remote_specification)).to be(spec)
+      subject.__swap__(new_spec)
+      expect(subject.instance_variable_get(:@_remote_specification)).to be(new_spec)
+    end
+  end
+
+  describe "#sort_obj" do
+    context "when platform is ruby" do
+      it "should return a sorting delegate array with name, version, and -1" do
+        expect(subject.sort_obj).to match_array(["foo", version, -1])
+      end
+    end
+
+    context "when platform is not ruby" do
+      let(:platform) { "jruby" }
+
+      it "should return a sorting delegate array with name, version, and 1" do
+        expect(subject.sort_obj).to match_array(["foo", version, 1])
+      end
+    end
+  end
+
+  describe "method missing" do
+    context "and is present in Gem::Specification" do
+      let(:remote_spec) { double(:remote_spec, :authors => "abcd") }
+
+      before do
+        allow(subject).to receive(:_remote_specification).and_return(remote_spec)
+        expect(subject.methods.map(&:to_sym)).not_to include(:authors)
+      end
+
+      it "should send through to Gem::Specification" do
+        expect(subject.authors).to eq("abcd")
+      end
+    end
+  end
+
+  describe "respond to missing?" do
+    context "and is present in Gem::Specification" do
+      let(:remote_spec) { double(:remote_spec, :authors => "abcd") }
+
+      before do
+        allow(subject).to receive(:_remote_specification).and_return(remote_spec)
+        expect(subject.methods.map(&:to_sym)).not_to include(:authors)
+      end
+
+      it "should send through to Gem::Specification" do
+        expect(subject.respond_to?(:authors)).to be_truthy
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/retry_spec.rb b/spec/bundler/bundler/retry_spec.rb
new file mode 100644
index 0000000000..b893580d72
--- /dev/null
+++ b/spec/bundler/bundler/retry_spec.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Retry do
+  it "return successful result if no errors" do
+    attempts = 0
+    result = Bundler::Retry.new(nil, nil, 3).attempt do
+      attempts += 1
+      :success
+    end
+    expect(result).to eq(:success)
+    expect(attempts).to eq(1)
+  end
+
+  it "returns the first valid result" do
+    jobs = [proc { raise "foo" }, proc { :bar }, proc { raise "foo" }]
+    attempts = 0
+    result = Bundler::Retry.new(nil, nil, 3).attempt do
+      attempts += 1
+      jobs.shift.call
+    end
+    expect(result).to eq(:bar)
+    expect(attempts).to eq(2)
+  end
+
+  it "raises the last error" do
+    errors = [StandardError, StandardError, StandardError, Bundler::GemfileNotFound]
+    attempts = 0
+    expect do
+      Bundler::Retry.new(nil, nil, 3).attempt do
+        attempts += 1
+        raise errors.shift
+      end
+    end.to raise_error(Bundler::GemfileNotFound)
+    expect(attempts).to eq(4)
+  end
+
+  it "raises exceptions" do
+    error = Bundler::GemfileNotFound
+    attempts = 0
+    expect do
+      Bundler::Retry.new(nil, error).attempt do
+        attempts += 1
+        raise error
+      end
+    end.to raise_error(error)
+    expect(attempts).to eq(1)
+  end
+
+  context "logging" do
+    let(:error)           { Bundler::GemfileNotFound }
+    let(:failure_message) { "Retrying test due to error (2/2): #{error} #{error}" }
+
+    context "with debugging on" do
+      it "print error message with newline" do
+        allow(Bundler.ui).to receive(:debug?).and_return(true)
+        expect(Bundler.ui).to_not receive(:info)
+        expect(Bundler.ui).to receive(:warn).with(failure_message, true)
+
+        expect do
+          Bundler::Retry.new("test", [], 1).attempt do
+            raise error
+          end
+        end.to raise_error(error)
+      end
+    end
+
+    context "with debugging off" do
+      it "print error message with newlines" do
+        allow(Bundler.ui).to  receive(:debug?).and_return(false)
+        expect(Bundler.ui).to receive(:info).with("").twice
+        expect(Bundler.ui).to receive(:warn).with(failure_message, false)
+
+        expect do
+          Bundler::Retry.new("test", [], 1).attempt do
+            raise error
+          end
+        end.to raise_error(error)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/ruby_dsl_spec.rb b/spec/bundler/bundler/ruby_dsl_spec.rb
new file mode 100644
index 0000000000..bc1ca98457
--- /dev/null
+++ b/spec/bundler/bundler/ruby_dsl_spec.rb
@@ -0,0 +1,95 @@
+# frozen_string_literal: true
+
+require "bundler/ruby_dsl"
+
+RSpec.describe Bundler::RubyDsl do
+  class MockDSL
+    include Bundler::RubyDsl
+
+    attr_reader :ruby_version
+  end
+
+  let(:dsl) { MockDSL.new }
+  let(:ruby_version) { "2.0.0" }
+  let(:version) { "2.0.0" }
+  let(:engine) { "jruby" }
+  let(:engine_version) { "9000" }
+  let(:patchlevel) { "100" }
+  let(:options) do
+    { :patchlevel => patchlevel,
+      :engine => engine,
+      :engine_version => engine_version }
+  end
+
+  let(:invoke) do
+    proc do
+      args = Array(ruby_version) + [options]
+      dsl.ruby(*args)
+    end
+  end
+
+  subject do
+    invoke.call
+    dsl.ruby_version
+  end
+
+  describe "#ruby_version" do
+    shared_examples_for "it stores the ruby version" do
+      it "stores the version" do
+        expect(subject.versions).to eq(Array(ruby_version))
+        expect(subject.gem_version.version).to eq(version)
+      end
+
+      it "stores the engine details" do
+        expect(subject.engine).to eq(engine)
+        expect(subject.engine_versions).to eq(Array(engine_version))
+      end
+
+      it "stores the patchlevel" do
+        expect(subject.patchlevel).to eq(patchlevel)
+      end
+    end
+
+    context "with a plain version" do
+      it_behaves_like "it stores the ruby version"
+    end
+
+    context "with a single requirement" do
+      let(:ruby_version) { ">= 2.0.0" }
+      it_behaves_like "it stores the ruby version"
+    end
+
+    context "with two requirements in the same string" do
+      let(:ruby_version) { ">= 2.0.0, < 3.0" }
+      it "raises an error" do
+        expect { subject }.to raise_error(ArgumentError)
+      end
+    end
+
+    context "with two requirements" do
+      let(:ruby_version) { ["~> 2.0.0", "> 2.0.1"] }
+      it_behaves_like "it stores the ruby version"
+    end
+
+    context "with multiple engine versions" do
+      let(:engine_version) { ["> 200", "< 300"] }
+      it_behaves_like "it stores the ruby version"
+    end
+
+    context "with no options hash" do
+      let(:invoke) { proc { dsl.ruby(ruby_version) } }
+
+      let(:patchlevel) { nil }
+      let(:engine) { "ruby" }
+      let(:engine_version) { version }
+
+      it_behaves_like "it stores the ruby version"
+
+      context "and with multiple requirements" do
+        let(:ruby_version) { ["~> 2.0.0", "> 2.0.1"] }
+        let(:engine_version) { ruby_version }
+        it_behaves_like "it stores the ruby version"
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/ruby_version_spec.rb b/spec/bundler/bundler/ruby_version_spec.rb
new file mode 100644
index 0000000000..46a1b2918b
--- /dev/null
+++ b/spec/bundler/bundler/ruby_version_spec.rb
@@ -0,0 +1,524 @@
+# frozen_string_literal: true
+
+require "bundler/ruby_version"
+
+RSpec.describe "Bundler::RubyVersion and its subclasses" do
+  let(:version)              { "2.0.0" }
+  let(:patchlevel)           { "645" }
+  let(:engine)               { "jruby" }
+  let(:engine_version)       { "2.0.1" }
+
+  describe Bundler::RubyVersion do
+    subject { Bundler::RubyVersion.new(version, patchlevel, engine, engine_version) }
+
+    let(:ruby_version)         { subject }
+    let(:other_version)        { version }
+    let(:other_patchlevel)     { patchlevel }
+    let(:other_engine)         { engine }
+    let(:other_engine_version) { engine_version }
+    let(:other_ruby_version)   { Bundler::RubyVersion.new(other_version, other_patchlevel, other_engine, other_engine_version) }
+
+    describe "#initialize" do
+      context "no engine is passed" do
+        let(:engine) { nil }
+
+        it "should set ruby as the engine" do
+          expect(subject.engine).to eq("ruby")
+        end
+      end
+
+      context "no engine_version is passed" do
+        let(:engine_version) { nil }
+
+        it "should set engine version as the passed version" do
+          expect(subject.engine_versions).to eq(["2.0.0"])
+        end
+      end
+
+      context "with engine in symbol" do
+        let(:engine) { :jruby }
+
+        it "should coerce engine to string" do
+          expect(subject.engine).to eq("jruby")
+        end
+      end
+
+      context "is called with multiple requirements" do
+        let(:version) { ["<= 2.0.0", "> 1.9.3"] }
+        let(:engine_version) { nil }
+
+        it "sets the versions" do
+          expect(subject.versions).to eq(version)
+        end
+
+        it "sets the engine versions" do
+          expect(subject.engine_versions).to eq(version)
+        end
+      end
+
+      context "is called with multiple engine requirements" do
+        let(:engine_version) { [">= 2.0", "< 2.3"] }
+
+        it "sets the engine versions" do
+          expect(subject.engine_versions).to eq(engine_version)
+        end
+      end
+    end
+
+    describe ".from_string" do
+      shared_examples_for "returning" do
+        it "returns the original RubyVersion" do
+          expect(described_class.from_string(subject.to_s)).to eq(subject)
+        end
+      end
+
+      include_examples "returning"
+
+      context "no patchlevel" do
+        let(:patchlevel) { nil }
+
+        include_examples "returning"
+      end
+
+      context "engine is ruby" do
+        let(:engine) { "ruby" }
+        let(:engine_version) { version }
+
+        include_examples "returning"
+      end
+
+      context "with multiple requirements" do
+        let(:engine_version) { ["> 9", "< 11"] }
+        let(:version) { ["> 8", "< 10"] }
+        let(:patchlevel) { nil }
+
+        it "returns nil" do
+          expect(described_class.from_string(subject.to_s)).to be_nil
+        end
+      end
+    end
+
+    describe "#to_s" do
+      it "should return info string with the ruby version, patchlevel, engine, and engine version" do
+        expect(subject.to_s).to eq("ruby 2.0.0p645 (jruby 2.0.1)")
+      end
+
+      context "no patchlevel" do
+        let(:patchlevel) { nil }
+
+        it "should return info string with the version, engine, and engine version" do
+          expect(subject.to_s).to eq("ruby 2.0.0 (jruby 2.0.1)")
+        end
+      end
+
+      context "engine is ruby" do
+        let(:engine) { "ruby" }
+
+        it "should return info string with the ruby version and patchlevel" do
+          expect(subject.to_s).to eq("ruby 2.0.0p645")
+        end
+      end
+
+      context "with multiple requirements" do
+        let(:engine_version) { ["> 9", "< 11"] }
+        let(:version) { ["> 8", "< 10"] }
+        let(:patchlevel) { nil }
+
+        it "should return info string with all requirements" do
+          expect(subject.to_s).to eq("ruby > 8, < 10 (jruby > 9, < 11)")
+        end
+      end
+    end
+
+    describe "#==" do
+      shared_examples_for "two ruby versions are not equal" do
+        it "should return false" do
+          expect(subject).to_not eq(other_ruby_version)
+        end
+      end
+
+      context "the versions, pathlevels, engines, and engine_versions match" do
+        it "should return true" do
+          expect(subject).to eq(other_ruby_version)
+        end
+      end
+
+      context "the versions do not match" do
+        let(:other_version) { "1.21.6" }
+
+        it_behaves_like "two ruby versions are not equal"
+      end
+
+      context "the patchlevels do not match" do
+        let(:other_patchlevel) { "21" }
+
+        it_behaves_like "two ruby versions are not equal"
+      end
+
+      context "the engines do not match" do
+        let(:other_engine) { "ruby" }
+
+        it_behaves_like "two ruby versions are not equal"
+      end
+
+      context "the engine versions do not match" do
+        let(:other_engine_version) { "1.11.2" }
+
+        it_behaves_like "two ruby versions are not equal"
+      end
+    end
+
+    describe "#host" do
+      before do
+        allow(RbConfig::CONFIG).to receive(:[]).with("host_cpu").and_return("x86_64")
+        allow(RbConfig::CONFIG).to receive(:[]).with("host_vendor").and_return("apple")
+        allow(RbConfig::CONFIG).to receive(:[]).with("host_os").and_return("darwin14.5.0")
+      end
+
+      it "should return an info string with the host cpu, vendor, and os" do
+        expect(subject.host).to eq("x86_64-apple-darwin14.5.0")
+      end
+
+      it "memoizes the info string with the host cpu, vendor, and os" do
+        expect(RbConfig::CONFIG).to receive(:[]).with("host_cpu").once.and_call_original
+        expect(RbConfig::CONFIG).to receive(:[]).with("host_vendor").once.and_call_original
+        expect(RbConfig::CONFIG).to receive(:[]).with("host_os").once.and_call_original
+        2.times { ruby_version.host }
+      end
+    end
+
+    describe "#gem_version" do
+      let(:gem_version) { "2.0.0" }
+      let(:gem_version_obj) { Gem::Version.new(gem_version) }
+
+      shared_examples_for "it parses the version from the requirement string" do |version|
+        let(:version) { version }
+        it "should return the underlying version" do
+          expect(ruby_version.gem_version).to eq(gem_version_obj)
+          expect(ruby_version.gem_version.version).to eq(gem_version)
+        end
+      end
+
+      it_behaves_like "it parses the version from the requirement string", "2.0.0"
+      it_behaves_like "it parses the version from the requirement string", ">= 2.0.0"
+      it_behaves_like "it parses the version from the requirement string", "~> 2.0.0"
+      it_behaves_like "it parses the version from the requirement string", "< 2.0.0"
+      it_behaves_like "it parses the version from the requirement string", "= 2.0.0"
+      it_behaves_like "it parses the version from the requirement string", ["> 2.0.0", "< 2.4.5"]
+    end
+
+    describe "#diff" do
+      let(:engine) { "ruby" }
+
+      shared_examples_for "there is a difference in the engines" do
+        it "should return a tuple with :engine and the two different engines" do
+          expect(ruby_version.diff(other_ruby_version)).to eq([:engine, engine, other_engine])
+        end
+      end
+
+      shared_examples_for "there is a difference in the versions" do
+        it "should return a tuple with :version and the two different versions" do
+          expect(ruby_version.diff(other_ruby_version)).to eq([:version, Array(version).join(", "), Array(other_version).join(", ")])
+        end
+      end
+
+      shared_examples_for "there is a difference in the engine versions" do
+        it "should return a tuple with :engine_version and the two different engine versions" do
+          expect(ruby_version.diff(other_ruby_version)).to eq([:engine_version, Array(engine_version).join(", "), Array(other_engine_version).join(", ")])
+        end
+      end
+
+      shared_examples_for "there is a difference in the patchlevels" do
+        it "should return a tuple with :patchlevel and the two different patchlevels" do
+          expect(ruby_version.diff(other_ruby_version)).to eq([:patchlevel, patchlevel, other_patchlevel])
+        end
+      end
+
+      shared_examples_for "there are no differences" do
+        it "should return nil" do
+          expect(ruby_version.diff(other_ruby_version)).to be_nil
+        end
+      end
+
+      context "all things match exactly" do
+        it_behaves_like "there are no differences"
+      end
+
+      context "detects engine discrepancies first" do
+        let(:other_version)        { "2.0.1" }
+        let(:other_patchlevel)     { "643" }
+        let(:other_engine)         { "rbx" }
+        let(:other_engine_version) { "2.0.0" }
+
+        it_behaves_like "there is a difference in the engines"
+      end
+
+      context "detects version discrepancies second" do
+        let(:other_version)        { "2.0.1" }
+        let(:other_patchlevel)     { "643" }
+        let(:other_engine_version) { "2.0.0" }
+
+        it_behaves_like "there is a difference in the versions"
+      end
+
+      context "detects version discrepancies with multiple requirements second" do
+        let(:other_version)        { "2.0.1" }
+        let(:other_patchlevel)     { "643" }
+        let(:other_engine_version) { "2.0.0" }
+
+        let(:version) { ["> 2.0.0", "< 1.0.0"] }
+
+        it_behaves_like "there is a difference in the versions"
+      end
+
+      context "detects engine version discrepancies third" do
+        let(:other_patchlevel)     { "643" }
+        let(:other_engine_version) { "2.0.0" }
+
+        it_behaves_like "there is a difference in the engine versions"
+      end
+
+      context "detects engine version discrepancies with multiple requirements third" do
+        let(:other_patchlevel)     { "643" }
+        let(:other_engine_version) { "2.0.0" }
+
+        let(:engine_version) { ["> 2.0.0", "< 1.0.0"] }
+
+        it_behaves_like "there is a difference in the engine versions"
+      end
+
+      context "detects patchlevel discrepancies last" do
+        let(:other_patchlevel) { "643" }
+
+        it_behaves_like "there is a difference in the patchlevels"
+      end
+
+      context "successfully matches gem requirements" do
+        let(:version)              { ">= 2.0.0" }
+        let(:patchlevel)           { "< 643" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { "~> 2.0.1" }
+        let(:other_version)        { "2.0.0" }
+        let(:other_patchlevel)     { "642" }
+        let(:other_engine)         { "ruby" }
+        let(:other_engine_version) { "2.0.5" }
+
+        it_behaves_like "there are no differences"
+      end
+
+      context "successfully matches multiple gem requirements" do
+        let(:version)              { [">= 2.0.0", "< 2.4.5"] }
+        let(:patchlevel)           { "< 643" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { ["~> 2.0.1", "< 2.4.5"] }
+        let(:other_version)        { "2.0.0" }
+        let(:other_patchlevel)     { "642" }
+        let(:other_engine)         { "ruby" }
+        let(:other_engine_version) { "2.0.5" }
+
+        it_behaves_like "there are no differences"
+      end
+
+      context "successfully detects bad gem requirements with versions with multiple requirements" do
+        let(:version)              { ["~> 2.0.0", "< 2.0.5"] }
+        let(:patchlevel)           { "< 643" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { "~> 2.0.1" }
+        let(:other_version)        { "2.0.5" }
+        let(:other_patchlevel)     { "642" }
+        let(:other_engine)         { "ruby" }
+        let(:other_engine_version) { "2.0.5" }
+
+        it_behaves_like "there is a difference in the versions"
+      end
+
+      context "successfully detects bad gem requirements with versions" do
+        let(:version)              { "~> 2.0.0" }
+        let(:patchlevel)           { "< 643" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { "~> 2.0.1" }
+        let(:other_version)        { "2.1.0" }
+        let(:other_patchlevel)     { "642" }
+        let(:other_engine)         { "ruby" }
+        let(:other_engine_version) { "2.0.5" }
+
+        it_behaves_like "there is a difference in the versions"
+      end
+
+      context "successfully detects bad gem requirements with patchlevels" do
+        let(:version)              { ">= 2.0.0" }
+        let(:patchlevel)           { "< 643" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { "~> 2.0.1" }
+        let(:other_version)        { "2.0.0" }
+        let(:other_patchlevel)     { "645" }
+        let(:other_engine)         { "ruby" }
+        let(:other_engine_version) { "2.0.5" }
+
+        it_behaves_like "there is a difference in the patchlevels"
+      end
+
+      context "successfully detects bad gem requirements with engine versions" do
+        let(:version)              { ">= 2.0.0" }
+        let(:patchlevel)           { "< 643" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { "~> 2.0.1" }
+        let(:other_version)        { "2.0.0" }
+        let(:other_patchlevel)     { "642" }
+        let(:other_engine)         { "ruby" }
+        let(:other_engine_version) { "2.1.0" }
+
+        it_behaves_like "there is a difference in the engine versions"
+      end
+
+      context "with a patchlevel of -1" do
+        let(:version)              { ">= 2.0.0" }
+        let(:patchlevel)           { "-1" }
+        let(:engine)               { "ruby" }
+        let(:engine_version)       { "~> 2.0.1" }
+        let(:other_version)        { version }
+        let(:other_engine)         { engine }
+        let(:other_engine_version) { engine_version }
+
+        context "and comparing with another patchlevel of -1" do
+          let(:other_patchlevel) { patchlevel }
+
+          it_behaves_like "there are no differences"
+        end
+
+        context "and comparing with a patchlevel that is not -1" do
+          let(:other_patchlevel)     { "642" }
+
+          it_behaves_like "there is a difference in the patchlevels"
+        end
+      end
+    end
+
+    describe "#system" do
+      subject { Bundler::RubyVersion.system }
+
+      let(:bundler_system_ruby_version) { subject }
+
+      before do
+        Bundler::RubyVersion.instance_variable_set("@ruby_version", nil)
+      end
+
+      it "should return an instance of Bundler::RubyVersion" do
+        expect(subject).to be_kind_of(Bundler::RubyVersion)
+      end
+
+      it "memoizes the instance of Bundler::RubyVersion" do
+        expect(Bundler::RubyVersion).to receive(:new).once.and_call_original
+        2.times { subject }
+      end
+
+      describe "#version" do
+        it "should return a copy of the value of RUBY_VERSION" do
+          expect(subject.versions).to eq([RUBY_VERSION])
+          expect(subject.versions.first).to_not be(RUBY_VERSION)
+        end
+      end
+
+      describe "#engine" do
+        context "RUBY_ENGINE is defined" do
+          before { stub_const("RUBY_ENGINE", "jruby") }
+          before { stub_const("JRUBY_VERSION", "2.1.1") }
+
+          it "should return a copy of the value of RUBY_ENGINE" do
+            expect(subject.engine).to eq("jruby")
+            expect(subject.engine).to_not be(RUBY_ENGINE)
+          end
+        end
+
+        context "RUBY_ENGINE is not defined" do
+          before { stub_const("RUBY_ENGINE", nil) }
+
+          it "should return the string 'ruby'" do
+            expect(subject.engine).to eq("ruby")
+          end
+        end
+      end
+
+      describe "#engine_version" do
+        context "engine is ruby" do
+          before do
+            stub_const("RUBY_VERSION", "2.2.4")
+            stub_const("RUBY_ENGINE", "ruby")
+          end
+
+          it "should return a copy of the value of RUBY_VERSION" do
+            expect(bundler_system_ruby_version.engine_versions).to eq(["2.2.4"])
+            expect(bundler_system_ruby_version.engine_versions.first).to_not be(RUBY_VERSION)
+          end
+        end
+
+        context "engine is rbx" do
+          before do
+            stub_const("RUBY_ENGINE", "rbx")
+            stub_const("Rubinius::VERSION", "2.0.0")
+          end
+
+          it "should return a copy of the value of Rubinius::VERSION" do
+            expect(bundler_system_ruby_version.engine_versions).to eq(["2.0.0"])
+            expect(bundler_system_ruby_version.engine_versions.first).to_not be(Rubinius::VERSION)
+          end
+        end
+
+        context "engine is jruby" do
+          before do
+            stub_const("RUBY_ENGINE", "jruby")
+            stub_const("JRUBY_VERSION", "2.1.1")
+          end
+
+          it "should return a copy of the value of JRUBY_VERSION" do
+            expect(subject.engine_versions).to eq(["2.1.1"])
+            expect(bundler_system_ruby_version.engine_versions.first).to_not be(JRUBY_VERSION)
+          end
+        end
+
+        context "engine is some other ruby engine" do
+          before do
+            stub_const("RUBY_ENGINE", "not_supported_ruby_engine")
+            stub_const("RUBY_ENGINE_VERSION", "1.2.3")
+          end
+
+          it "returns RUBY_ENGINE_VERSION" do
+            expect(bundler_system_ruby_version.engine_versions).to eq(["1.2.3"])
+          end
+        end
+      end
+
+      describe "#patchlevel" do
+        it "should return a string with the value of RUBY_PATCHLEVEL" do
+          expect(subject.patchlevel).to eq(RUBY_PATCHLEVEL.to_s)
+        end
+      end
+    end
+
+    describe "#to_gem_version_with_patchlevel" do
+      shared_examples_for "the patchlevel is omitted" do
+        it "does not include a patch level" do
+          expect(subject.to_gem_version_with_patchlevel.to_s).to eq(version)
+        end
+      end
+
+      context "with nil patch number" do
+        let(:patchlevel) { nil }
+
+        it_behaves_like "the patchlevel is omitted"
+      end
+
+      context "with negative patch number" do
+        let(:patchlevel) { -1 }
+
+        it_behaves_like "the patchlevel is omitted"
+      end
+
+      context "with a valid patch number" do
+        it "uses the specified patchlevel as patchlevel" do
+          expect(subject.to_gem_version_with_patchlevel.to_s).to eq("#{version}.#{patchlevel}")
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/rubygems_integration_spec.rb b/spec/bundler/bundler/rubygems_integration_spec.rb
new file mode 100644
index 0000000000..b1b15d9e5d
--- /dev/null
+++ b/spec/bundler/bundler/rubygems_integration_spec.rb
@@ -0,0 +1,114 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::RubygemsIntegration do
+  it "uses the same chdir lock as rubygems", :rubygems => "2.1" do
+    expect(Bundler.rubygems.ext_lock).to eq(Gem::Ext::Builder::CHDIR_MONITOR)
+  end
+
+  context "#validate" do
+    let(:spec) do
+      Gem::Specification.new do |s|
+        s.name = "to-validate"
+        s.version = "1.0.0"
+        s.loaded_from = __FILE__
+      end
+    end
+    subject { Bundler.rubygems.validate(spec) }
+
+    it "skips overly-strict gemspec validation", :rubygems => "< 1.7" do
+      expect(spec).to_not receive(:validate)
+      subject
+    end
+
+    it "validates with packaging mode disabled", :rubygems => "1.7" do
+      expect(spec).to receive(:validate).with(false)
+      subject
+    end
+
+    it "should set a summary to avoid an overly-strict error", :rubygems => "~> 1.7.0" do
+      spec.summary = nil
+      expect { subject }.not_to raise_error
+      expect(spec.summary).to eq("")
+    end
+
+    context "with an invalid spec" do
+      before do
+        expect(spec).to receive(:validate).with(false).
+          and_raise(Gem::InvalidSpecificationException.new("TODO is not an author"))
+      end
+
+      it "should raise a Gem::InvalidSpecificationException and produce a helpful warning message",
+        :rubygems => "1.7" do
+        expect { subject }.to raise_error(Gem::InvalidSpecificationException,
+          "The gemspec at #{__FILE__} is not valid. "\
+          "Please fix this gemspec.\nThe validation error was 'TODO is not an author'\n")
+      end
+    end
+  end
+
+  describe "#configuration" do
+    it "handles Gem::SystemExitException errors" do
+      allow(Gem).to receive(:configuration) { raise Gem::SystemExitException.new(1) }
+      expect { Bundler.rubygems.configuration }.to raise_error(Gem::SystemExitException)
+    end
+  end
+
+  describe "#download_gem", :rubygems => ">= 2.0" do
+    let(:bundler_retry) { double(Bundler::Retry) }
+    let(:retry) { double("Bundler::Retry") }
+    let(:uri) {  URI.parse("https://foo.bar") }
+    let(:path) { Gem.path.first }
+    let(:spec) do
+      spec = Bundler::RemoteSpecification.new("Foo", Gem::Version.new("2.5.2"),
+        Gem::Platform::RUBY, nil)
+      spec.remote = Bundler::Source::Rubygems::Remote.new(uri.to_s)
+      spec
+    end
+    let(:fetcher) { double("gem_remote_fetcher") }
+
+    it "successfully downloads gem with retries" do
+      expect(Bundler.rubygems).to receive(:gem_remote_fetcher).and_return(fetcher)
+      expect(fetcher).to receive(:headers=).with("X-Gemfile-Source" => "https://foo.bar")
+      expect(Bundler::Retry).to receive(:new).with("download gem from #{uri}/").
+        and_return(bundler_retry)
+      expect(bundler_retry).to receive(:attempts).and_yield
+      expect(fetcher).to receive(:download).with(spec, uri, path)
+
+      Bundler.rubygems.download_gem(spec, uri, path)
+    end
+  end
+
+  describe "#fetch_all_remote_specs", :rubygems => ">= 2.0" do
+    let(:uri) { URI("https://example.com") }
+    let(:fetcher) { double("gem_remote_fetcher") }
+    let(:specs_response) { Marshal.dump(["specs"]) }
+    let(:prerelease_specs_response) { Marshal.dump(["prerelease_specs"]) }
+
+    context "when a rubygems source mirror is set" do
+      let(:orig_uri) { URI("http://zombo.com") }
+      let(:remote_with_mirror) { double("remote", :uri => uri, :original_uri => orig_uri) }
+
+      it "sets the 'X-Gemfile-Source' header containing the original source" do
+        expect(Bundler.rubygems).to receive(:gem_remote_fetcher).twice.and_return(fetcher)
+        expect(fetcher).to receive(:headers=).with("X-Gemfile-Source" => "http://zombo.com").twice
+        expect(fetcher).to receive(:fetch_path).with(uri + "specs.4.8.gz").and_return(specs_response)
+        expect(fetcher).to receive(:fetch_path).with(uri + "prerelease_specs.4.8.gz").and_return(prerelease_specs_response)
+        result = Bundler.rubygems.fetch_all_remote_specs(remote_with_mirror)
+        expect(result).to eq(%w[specs prerelease_specs])
+      end
+    end
+
+    context "when there is no rubygems source mirror set" do
+      let(:remote_no_mirror) { double("remote", :uri => uri, :original_uri => nil) }
+
+      it "does not set the 'X-Gemfile-Source' header" do
+        expect(Bundler.rubygems).to receive(:gem_remote_fetcher).twice.and_return(fetcher)
+        expect(fetcher).to_not receive(:headers=)
+        expect(fetcher).to receive(:fetch_path).with(uri + "specs.4.8.gz").and_return(specs_response)
+        expect(fetcher).to receive(:fetch_path).with(uri + "prerelease_specs.4.8.gz").and_return(prerelease_specs_response)
+        result = Bundler.rubygems.fetch_all_remote_specs(remote_no_mirror)
+        expect(result).to eq(%w[specs prerelease_specs])
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/settings/validator_spec.rb b/spec/bundler/bundler/settings/validator_spec.rb
new file mode 100644
index 0000000000..e4ffd89435
--- /dev/null
+++ b/spec/bundler/bundler/settings/validator_spec.rb
@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Settings::Validator do
+  describe ".validate!" do
+    def validate!(key, value, settings)
+      transformed_key = Bundler.settings.key_for(key)
+      if value.nil?
+        settings.delete(transformed_key)
+      else
+        settings[transformed_key] = value
+      end
+      described_class.validate!(key, value, settings)
+      settings
+    end
+
+    it "path and path.system are mutually exclusive" do
+      expect(validate!("path", "bundle", {})).to eq("BUNDLE_PATH" => "bundle")
+      expect(validate!("path", "bundle", "BUNDLE_PATH__SYSTEM" => false)).to eq("BUNDLE_PATH" => "bundle")
+      expect(validate!("path", "bundle", "BUNDLE_PATH__SYSTEM" => true)).to eq("BUNDLE_PATH" => "bundle")
+      expect(validate!("path", nil, "BUNDLE_PATH__SYSTEM" => true)).to eq("BUNDLE_PATH__SYSTEM" => true)
+      expect(validate!("path", nil, "BUNDLE_PATH__SYSTEM" => false)).to eq("BUNDLE_PATH__SYSTEM" => false)
+      expect(validate!("path", nil, {})).to eq({})
+
+      expect(validate!("path.system", true, "BUNDLE_PATH" => "bundle")).to eq("BUNDLE_PATH__SYSTEM" => true)
+      expect(validate!("path.system", false, "BUNDLE_PATH" => "bundle")).to eq("BUNDLE_PATH" => "bundle", "BUNDLE_PATH__SYSTEM" => false)
+      expect(validate!("path.system", nil, "BUNDLE_PATH" => "bundle")).to eq("BUNDLE_PATH" => "bundle")
+      expect(validate!("path.system", true, {})).to eq("BUNDLE_PATH__SYSTEM" => true)
+      expect(validate!("path.system", false, {})).to eq("BUNDLE_PATH__SYSTEM" => false)
+      expect(validate!("path.system", nil, {})).to eq({})
+    end
+
+    it "a group cannot be in both `with` & `without` simultaneously" do
+      expect do
+        validate!("with", "", {})
+        validate!("with", nil, {})
+        validate!("with", "", "BUNDLE_WITHOUT" => "a")
+        validate!("with", nil, "BUNDLE_WITHOUT" => "a")
+        validate!("with", "b:c", "BUNDLE_WITHOUT" => "a")
+
+        validate!("without", "", {})
+        validate!("without", nil, {})
+        validate!("without", "", "BUNDLE_WITH" => "a")
+        validate!("without", nil, "BUNDLE_WITH" => "a")
+        validate!("without", "b:c", "BUNDLE_WITH" => "a")
+      end.not_to raise_error
+
+      expect { validate!("with", "b:c", "BUNDLE_WITHOUT" => "c:d") }.to raise_error Bundler::InvalidOption, strip_whitespace(<<-EOS).strip
+        Setting `with` to "b:c" failed:
+         - a group cannot be in both `with` & `without` simultaneously
+         - `without` is current set to [:c, :d]
+         - the `c` groups conflict
+      EOS
+
+      expect { validate!("without", "b:c", "BUNDLE_WITH" => "c:d") }.to raise_error Bundler::InvalidOption, strip_whitespace(<<-EOS).strip
+        Setting `without` to "b:c" failed:
+         - a group cannot be in both `with` & `without` simultaneously
+         - `with` is current set to [:c, :d]
+         - the `c` groups conflict
+      EOS
+    end
+  end
+
+  describe described_class::Rule do
+    let(:keys) { %w[key] }
+    let(:description) { "rule description" }
+    let(:validate) { proc { raise "validate called!" } }
+    subject(:rule) { described_class.new(keys, description, &validate) }
+
+    describe "#validate!" do
+      it "calls the block" do
+        expect { rule.validate!("key", nil, {}) }.to raise_error(RuntimeError, /validate called!/)
+      end
+    end
+
+    describe "#fail!" do
+      it "raises with a helpful message" do
+        expect { subject.fail!("key", "value", "reason1", "reason2") }.to raise_error Bundler::InvalidOption, strip_whitespace(<<-EOS).strip
+          Setting `key` to "value" failed:
+           - rule description
+           - reason1
+           - reason2
+        EOS
+      end
+    end
+
+    describe "#set" do
+      it "works when the value has not changed" do
+        allow(Bundler.ui).to receive(:info).never
+
+        subject.set({}, "key", nil)
+        subject.set({ "BUNDLE_KEY" => "value" }, "key", "value")
+      end
+
+      it "prints out when the value is changing" do
+        settings = {}
+
+        expect(Bundler.ui).to receive(:info).with("Setting `key` to \"value\", since rule description, reason1")
+        subject.set(settings, "key", "value", "reason1")
+        expect(settings).to eq("BUNDLE_KEY" => "value")
+
+        expect(Bundler.ui).to receive(:info).with("Setting `key` to \"value2\", since rule description, reason2")
+        subject.set(settings, "key", "value2", "reason2")
+        expect(settings).to eq("BUNDLE_KEY" => "value2")
+
+        expect(Bundler.ui).to receive(:info).with("Setting `key` to nil, since rule description, reason3")
+        subject.set(settings, "key", nil, "reason3")
+        expect(settings).to eq({})
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/settings_spec.rb b/spec/bundler/bundler/settings_spec.rb
new file mode 100644
index 0000000000..1a31493e20
--- /dev/null
+++ b/spec/bundler/bundler/settings_spec.rb
@@ -0,0 +1,326 @@
+# frozen_string_literal: true
+
+require "bundler/settings"
+
+RSpec.describe Bundler::Settings do
+  subject(:settings) { described_class.new(bundled_app) }
+
+  describe "#set_local" do
+    context "when the local config file is not found" do
+      subject(:settings) { described_class.new(nil) }
+
+      it "raises a GemfileNotFound error with explanation" do
+        expect { subject.set_local("foo", "bar") }.
+          to raise_error(Bundler::GemfileNotFound, "Could not locate Gemfile")
+      end
+    end
+  end
+
+  describe "load_config" do
+    let(:hash) do
+      {
+        "build.thrift" => "--with-cppflags=-D_FORTIFY_SOURCE=0",
+        "build.libv8" => "--with-system-v8",
+        "build.therubyracer" => "--with-v8-dir",
+        "build.pg" => "--with-pg-config=/usr/local/Cellar/postgresql92/9.2.8_1/bin/pg_config",
+        "gem.coc" => "false",
+        "gem.mit" => "false",
+        "gem.test" => "minitest",
+        "thingy" => <<-EOS.tr("\n", " "),
+--asdf --fdsa --ty=oh man i hope this doesnt break bundler because
+that would suck --ehhh=oh geez it looks like i might have broken bundler somehow
+--very-important-option=DontDeleteRoo
+--very-important-option=DontDeleteRoo
+--very-important-option=DontDeleteRoo
+--very-important-option=DontDeleteRoo
+        EOS
+        "xyz" => "zyx",
+      }
+    end
+
+    before do
+      hash.each do |key, value|
+        settings.set_local key, value
+      end
+    end
+
+    it "can load the config" do
+      loaded = settings.send(:load_config, bundled_app("config"))
+      expected = Hash[hash.map do |k, v|
+        [settings.send(:key_for, k), v.to_s]
+      end]
+      expect(loaded).to eq(expected)
+    end
+
+    context "when BUNDLE_IGNORE_CONFIG is set" do
+      before { ENV["BUNDLE_IGNORE_CONFIG"] = "TRUE" }
+
+      it "ignores the config" do
+        loaded = settings.send(:load_config, bundled_app("config"))
+        expect(loaded).to eq({})
+      end
+    end
+  end
+
+  describe "#global_config_file" do
+    context "when $HOME is not accessible" do
+      context "when $TMPDIR is not writable" do
+        it "does not raise" do
+          expect(Bundler.rubygems).to receive(:user_home).twice.and_return(nil)
+          expect(FileUtils).to receive(:mkpath).twice.with(File.join(Dir.tmpdir, "bundler", "home")).and_raise(Errno::EROFS, "Read-only file system @ dir_s_mkdir - /tmp/bundler")
+
+          expect(subject.send(:global_config_file)).to be_nil
+        end
+      end
+    end
+  end
+
+  describe "#[]" do
+    context "when the local config file is not found" do
+      subject(:settings) { described_class.new }
+
+      it "does not raise" do
+        expect do
+          subject["foo"]
+        end.not_to raise_error
+      end
+    end
+
+    context "when not set" do
+      context "when default value present" do
+        it "retrieves value" do
+          expect(settings[:retry]).to be 3
+        end
+      end
+
+      it "returns nil" do
+        expect(settings[:buttermilk]).to be nil
+      end
+    end
+
+    context "when is boolean" do
+      it "returns a boolean" do
+        settings.set_local :frozen, "true"
+        expect(settings[:frozen]).to be true
+      end
+      context "when specific gem is configured" do
+        it "returns a boolean" do
+          settings.set_local "ignore_messages.foobar", "true"
+          expect(settings["ignore_messages.foobar"]).to be true
+        end
+      end
+    end
+
+    context "when is number" do
+      it "returns a number" do
+        settings.set_local :ssl_verify_mode, "1"
+        expect(settings[:ssl_verify_mode]).to be 1
+      end
+    end
+
+    context "when it's not possible to write to the file" do
+      it "raises an PermissionError with explanation" do
+        expect(bundler_fileutils).to receive(:mkdir_p).with(settings.send(:local_config_file).dirname).
+          and_raise(Errno::EACCES)
+        expect { settings.set_local :frozen, "1" }.
+          to raise_error(Bundler::PermissionError, /config/)
+      end
+    end
+  end
+
+  describe "#temporary" do
+    it "reset after used" do
+      Bundler.settings.set_local :no_install, true
+
+      Bundler.settings.temporary(:no_install => false) do
+        expect(Bundler.settings[:no_install]).to eq false
+      end
+
+      expect(Bundler.settings[:no_install]).to eq true
+    end
+
+    it "returns the return value of the block" do
+      ret = Bundler.settings.temporary({}) { :ret }
+      expect(ret).to eq :ret
+    end
+
+    context "when called without a block" do
+      it "leaves the setting changed" do
+        Bundler.settings.temporary(:foo => :random)
+        expect(Bundler.settings[:foo]).to eq "random"
+      end
+
+      it "returns nil" do
+        expect(Bundler.settings.temporary(:foo => :bar)).to be_nil
+      end
+    end
+  end
+
+  describe "#set_global" do
+    context "when it's not possible to write to the file" do
+      it "raises an PermissionError with explanation" do
+        expect(bundler_fileutils).to receive(:mkdir_p).with(settings.send(:global_config_file).dirname).
+          and_raise(Errno::EACCES)
+        expect { settings.set_global(:frozen, "1") }.
+          to raise_error(Bundler::PermissionError, %r{\.bundle/config})
+      end
+    end
+  end
+
+  describe "#pretty_values_for" do
+    it "prints the converted value rather than the raw string" do
+      bool_key = described_class::BOOL_KEYS.first
+      settings.set_local(bool_key, "false")
+      expect(subject.pretty_values_for(bool_key)).to eq [
+        "Set for your local app (#{bundled_app("config")}): false",
+      ]
+    end
+  end
+
+  describe "#mirror_for" do
+    let(:uri) { URI("https://rubygems.org/") }
+
+    context "with no configured mirror" do
+      it "returns the original URI" do
+        expect(settings.mirror_for(uri)).to eq(uri)
+      end
+
+      it "converts a string parameter to a URI" do
+        expect(settings.mirror_for("https://rubygems.org/")).to eq(uri)
+      end
+    end
+
+    context "with a configured mirror" do
+      let(:mirror_uri) { URI("https://rubygems-mirror.org/") }
+
+      before { settings.set_local "mirror.https://rubygems.org/", mirror_uri.to_s }
+
+      it "returns the mirror URI" do
+        expect(settings.mirror_for(uri)).to eq(mirror_uri)
+      end
+
+      it "converts a string parameter to a URI" do
+        expect(settings.mirror_for("https://rubygems.org/")).to eq(mirror_uri)
+      end
+
+      it "normalizes the URI" do
+        expect(settings.mirror_for("https://rubygems.org")).to eq(mirror_uri)
+      end
+
+      it "is case insensitive" do
+        expect(settings.mirror_for("HTTPS://RUBYGEMS.ORG/")).to eq(mirror_uri)
+      end
+
+      context "with a file URI" do
+        let(:mirror_uri) { URI("file:/foo/BAR/baz/qUx/") }
+
+        it "returns the mirror URI" do
+          expect(settings.mirror_for(uri)).to eq(mirror_uri)
+        end
+
+        it "converts a string parameter to a URI" do
+          expect(settings.mirror_for("file:/foo/BAR/baz/qUx/")).to eq(mirror_uri)
+        end
+
+        it "normalizes the URI" do
+          expect(settings.mirror_for("file:/foo/BAR/baz/qUx")).to eq(mirror_uri)
+        end
+      end
+    end
+  end
+
+  describe "#credentials_for" do
+    let(:uri) { URI("https://gemserver.example.org/") }
+    let(:credentials) { "username:password" }
+
+    context "with no configured credentials" do
+      it "returns nil" do
+        expect(settings.credentials_for(uri)).to be_nil
+      end
+    end
+
+    context "with credentials configured by URL" do
+      before { settings.set_local "https://gemserver.example.org/", credentials }
+
+      it "returns the configured credentials" do
+        expect(settings.credentials_for(uri)).to eq(credentials)
+      end
+    end
+
+    context "with credentials configured by hostname" do
+      before { settings.set_local "gemserver.example.org", credentials }
+
+      it "returns the configured credentials" do
+        expect(settings.credentials_for(uri)).to eq(credentials)
+      end
+    end
+  end
+
+  describe "URI normalization" do
+    it "normalizes HTTP URIs in credentials configuration" do
+      settings.set_local "http://gemserver.example.org", "username:password"
+      expect(settings.all).to include("http://gemserver.example.org/")
+    end
+
+    it "normalizes HTTPS URIs in credentials configuration" do
+      settings.set_local "https://gemserver.example.org", "username:password"
+      expect(settings.all).to include("https://gemserver.example.org/")
+    end
+
+    it "normalizes HTTP URIs in mirror configuration" do
+      settings.set_local "mirror.http://rubygems.org", "http://rubygems-mirror.org"
+      expect(settings.all).to include("mirror.http://rubygems.org/")
+    end
+
+    it "normalizes HTTPS URIs in mirror configuration" do
+      settings.set_local "mirror.https://rubygems.org", "http://rubygems-mirror.org"
+      expect(settings.all).to include("mirror.https://rubygems.org/")
+    end
+
+    it "does not normalize other config keys that happen to contain 'http'" do
+      settings.set_local "local.httparty", home("httparty")
+      expect(settings.all).to include("local.httparty")
+    end
+
+    it "does not normalize other config keys that happen to contain 'https'" do
+      settings.set_local "local.httpsmarty", home("httpsmarty")
+      expect(settings.all).to include("local.httpsmarty")
+    end
+
+    it "reads older keys without trailing slashes" do
+      settings.set_local "mirror.https://rubygems.org", "http://rubygems-mirror.org"
+      expect(settings.mirror_for("https://rubygems.org/")).to eq(
+        URI("http://rubygems-mirror.org/")
+      )
+    end
+
+    it "normalizes URIs with a fallback_timeout option" do
+      settings.set_local "mirror.https://rubygems.org/.fallback_timeout", "true"
+      expect(settings.all).to include("mirror.https://rubygems.org/.fallback_timeout")
+    end
+
+    it "normalizes URIs with a fallback_timeout option without a trailing slash" do
+      settings.set_local "mirror.https://rubygems.org.fallback_timeout", "true"
+      expect(settings.all).to include("mirror.https://rubygems.org/.fallback_timeout")
+    end
+  end
+
+  describe "BUNDLE_ keys format" do
+    let(:settings) { described_class.new(bundled_app(".bundle")) }
+
+    it "converts older keys without double dashes" do
+      config("BUNDLE_MY__PERSONAL.RACK" => "~/Work/git/rack")
+      expect(settings["my.personal.rack"]).to eq("~/Work/git/rack")
+    end
+
+    it "converts older keys without trailing slashes and double dashes" do
+      config("BUNDLE_MIRROR__HTTPS://RUBYGEMS.ORG" => "http://rubygems-mirror.org")
+      expect(settings["mirror.https://rubygems.org/"]).to eq("http://rubygems-mirror.org")
+    end
+
+    it "reads newer keys format properly" do
+      config("BUNDLE_MIRROR__HTTPS://RUBYGEMS__ORG/" => "http://rubygems-mirror.org")
+      expect(settings["mirror.https://rubygems.org/"]).to eq("http://rubygems-mirror.org")
+    end
+  end
+end
diff --git a/spec/bundler/bundler/shared_helpers_spec.rb b/spec/bundler/bundler/shared_helpers_spec.rb
new file mode 100644
index 0000000000..b66c43fd92
--- /dev/null
+++ b/spec/bundler/bundler/shared_helpers_spec.rb
@@ -0,0 +1,504 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::SharedHelpers do
+  let(:ext_lock_double) { double(:ext_lock) }
+
+  before do
+    allow(Bundler.rubygems).to receive(:ext_lock).and_return(ext_lock_double)
+    allow(ext_lock_double).to receive(:synchronize) {|&block| block.call }
+  end
+
+  subject { Bundler::SharedHelpers }
+
+  describe "#default_gemfile" do
+    before { ENV["BUNDLE_GEMFILE"] = "/path/Gemfile" }
+
+    context "Gemfile is present" do
+      let(:expected_gemfile_path) { Pathname.new("/path/Gemfile") }
+
+      it "returns the Gemfile path" do
+        expect(subject.default_gemfile).to eq(expected_gemfile_path)
+      end
+    end
+
+    context "Gemfile is not present" do
+      before { ENV["BUNDLE_GEMFILE"] = nil }
+
+      it "raises a GemfileNotFound error" do
+        expect { subject.default_gemfile }.to raise_error(
+          Bundler::GemfileNotFound, "Could not locate Gemfile"
+        )
+      end
+    end
+
+    context "Gemfile is not an absolute path" do
+      before { ENV["BUNDLE_GEMFILE"] = "Gemfile" }
+
+      let(:expected_gemfile_path) { Pathname.new("Gemfile").expand_path }
+
+      it "returns the Gemfile path" do
+        expect(subject.default_gemfile).to eq(expected_gemfile_path)
+      end
+    end
+  end
+
+  describe "#default_lockfile" do
+    context "gemfile is gems.rb" do
+      let(:gemfile_path)           { Pathname.new("/path/gems.rb") }
+      let(:expected_lockfile_path) { Pathname.new("/path/gems.locked") }
+
+      before { allow(subject).to receive(:default_gemfile).and_return(gemfile_path) }
+
+      it "returns the gems.locked path" do
+        expect(subject.default_lockfile).to eq(expected_lockfile_path)
+      end
+    end
+
+    context "is a regular Gemfile" do
+      let(:gemfile_path)           { Pathname.new("/path/Gemfile") }
+      let(:expected_lockfile_path) { Pathname.new("/path/Gemfile.lock") }
+
+      before { allow(subject).to receive(:default_gemfile).and_return(gemfile_path) }
+
+      it "returns the lock file path" do
+        expect(subject.default_lockfile).to eq(expected_lockfile_path)
+      end
+    end
+  end
+
+  describe "#default_bundle_dir" do
+    context ".bundle does not exist" do
+      it "returns nil" do
+        expect(subject.default_bundle_dir).to be_nil
+      end
+    end
+
+    context ".bundle is global .bundle" do
+      let(:global_rubygems_dir) { Pathname.new("#{bundled_app}") }
+
+      before do
+        Dir.mkdir ".bundle"
+        allow(Bundler.rubygems).to receive(:user_home).and_return(global_rubygems_dir)
+      end
+
+      it "returns nil" do
+        expect(subject.default_bundle_dir).to be_nil
+      end
+    end
+
+    context ".bundle is not global .bundle" do
+      let(:global_rubygems_dir)      { Pathname.new("/path/rubygems") }
+      let(:expected_bundle_dir_path) { Pathname.new("#{bundled_app}/.bundle") }
+
+      before do
+        Dir.mkdir ".bundle"
+        allow(Bundler.rubygems).to receive(:user_home).and_return(global_rubygems_dir)
+      end
+
+      it "returns the .bundle path" do
+        expect(subject.default_bundle_dir).to eq(expected_bundle_dir_path)
+      end
+    end
+  end
+
+  describe "#in_bundle?" do
+    it "calls the find_gemfile method" do
+      expect(subject).to receive(:find_gemfile)
+      subject.in_bundle?
+    end
+
+    shared_examples_for "correctly determines whether to return a Gemfile path" do
+      context "currently in directory with a Gemfile" do
+        before { File.new("Gemfile", "w") }
+
+        it "returns path of the bundle Gemfile" do
+          expect(subject.in_bundle?).to eq("#{bundled_app}/Gemfile")
+        end
+      end
+
+      context "currently in directory without a Gemfile" do
+        it "returns nil" do
+          expect(subject.in_bundle?).to be_nil
+        end
+      end
+    end
+
+    context "ENV['BUNDLE_GEMFILE'] set" do
+      before { ENV["BUNDLE_GEMFILE"] = "/path/Gemfile" }
+
+      it "returns ENV['BUNDLE_GEMFILE']" do
+        expect(subject.in_bundle?).to eq("/path/Gemfile")
+      end
+    end
+
+    context "ENV['BUNDLE_GEMFILE'] not set" do
+      before { ENV["BUNDLE_GEMFILE"] = nil }
+
+      it_behaves_like "correctly determines whether to return a Gemfile path"
+    end
+
+    context "ENV['BUNDLE_GEMFILE'] is blank" do
+      before { ENV["BUNDLE_GEMFILE"] = "" }
+
+      it_behaves_like "correctly determines whether to return a Gemfile path"
+    end
+  end
+
+  describe "#chdir" do
+    let(:op_block) { proc { Dir.mkdir "nested_dir" } }
+
+    before { Dir.mkdir "chdir_test_dir" }
+
+    it "executes the passed block while in the specified directory" do
+      subject.chdir("chdir_test_dir", &op_block)
+      expect(Pathname.new("chdir_test_dir/nested_dir")).to exist
+    end
+  end
+
+  describe "#pwd" do
+    it "returns the current absolute path" do
+      expect(subject.pwd).to eq(bundled_app)
+    end
+  end
+
+  describe "#with_clean_git_env" do
+    let(:with_clean_git_env_block) { proc { Dir.mkdir "with_clean_git_env_test_dir" } }
+
+    before do
+      ENV["GIT_DIR"] = "ORIGINAL_ENV_GIT_DIR"
+      ENV["GIT_WORK_TREE"] = "ORIGINAL_ENV_GIT_WORK_TREE"
+    end
+
+    it "executes the passed block" do
+      subject.with_clean_git_env(&with_clean_git_env_block)
+      expect(Pathname.new("with_clean_git_env_test_dir")).to exist
+    end
+
+    context "when a block is passed" do
+      let(:with_clean_git_env_block) do
+        proc do
+          Dir.mkdir "git_dir_test_dir" unless ENV["GIT_DIR"].nil?
+          Dir.mkdir "git_work_tree_test_dir" unless ENV["GIT_WORK_TREE"].nil?
+        end end
+
+      it "uses a fresh git env for execution" do
+        subject.with_clean_git_env(&with_clean_git_env_block)
+        expect(Pathname.new("git_dir_test_dir")).to_not exist
+        expect(Pathname.new("git_work_tree_test_dir")).to_not exist
+      end
+    end
+
+    context "passed block does not throw errors" do
+      let(:with_clean_git_env_block) do
+        proc do
+          ENV["GIT_DIR"] = "NEW_ENV_GIT_DIR"
+          ENV["GIT_WORK_TREE"] = "NEW_ENV_GIT_WORK_TREE"
+        end end
+
+      it "restores the git env after" do
+        subject.with_clean_git_env(&with_clean_git_env_block)
+        expect(ENV["GIT_DIR"]).to eq("ORIGINAL_ENV_GIT_DIR")
+        expect(ENV["GIT_WORK_TREE"]).to eq("ORIGINAL_ENV_GIT_WORK_TREE")
+      end
+    end
+
+    context "passed block throws errors" do
+      let(:with_clean_git_env_block) do
+        proc do
+          ENV["GIT_DIR"] = "NEW_ENV_GIT_DIR"
+          ENV["GIT_WORK_TREE"] = "NEW_ENV_GIT_WORK_TREE"
+          raise RuntimeError.new
+        end end
+
+      it "restores the git env after" do
+        expect { subject.with_clean_git_env(&with_clean_git_env_block) }.to raise_error(RuntimeError)
+        expect(ENV["GIT_DIR"]).to eq("ORIGINAL_ENV_GIT_DIR")
+        expect(ENV["GIT_WORK_TREE"]).to eq("ORIGINAL_ENV_GIT_WORK_TREE")
+      end
+    end
+  end
+
+  describe "#set_bundle_environment" do
+    before do
+      ENV["BUNDLE_GEMFILE"] = "Gemfile"
+    end
+
+    shared_examples_for "ENV['PATH'] gets set correctly" do
+      before { Dir.mkdir ".bundle" }
+
+      it "ensures bundle bin path is in ENV['PATH']" do
+        subject.set_bundle_environment
+        paths = ENV["PATH"].split(File::PATH_SEPARATOR)
+        expect(paths).to include("#{Bundler.bundle_path}/bin")
+      end
+    end
+
+    shared_examples_for "ENV['RUBYOPT'] gets set correctly" do
+      it "ensures -rbundler/setup is at the beginning of ENV['RUBYOPT']" do
+        subject.set_bundle_environment
+        expect(ENV["RUBYOPT"].split(" ")).to start_with("-rbundler/setup")
+      end
+    end
+
+    shared_examples_for "ENV['RUBYLIB'] gets set correctly" do
+      let(:ruby_lib_path) { "stubbed_ruby_lib_dir" }
+
+      before do
+        allow(Bundler::SharedHelpers).to receive(:bundler_ruby_lib).and_return(ruby_lib_path)
+      end
+
+      it "ensures bundler's ruby version lib path is in ENV['RUBYLIB']" do
+        subject.set_bundle_environment
+        paths = (ENV["RUBYLIB"]).split(File::PATH_SEPARATOR)
+        expect(paths).to include(ruby_lib_path)
+      end
+    end
+
+    it "calls the appropriate set methods" do
+      expect(subject).to receive(:set_path)
+      expect(subject).to receive(:set_rubyopt)
+      expect(subject).to receive(:set_rubylib)
+      subject.set_bundle_environment
+    end
+
+    it "exits if bundle path contains the unix-like path separator" do
+      if Gem.respond_to?(:path_separator)
+        allow(Gem).to receive(:path_separator).and_return(":")
+      else
+        stub_const("File::PATH_SEPARATOR", ":".freeze)
+      end
+      allow(Bundler).to receive(:bundle_path) { Pathname.new("so:me/dir/bin") }
+      expect { subject.send(:validate_bundle_path) }.to raise_error(
+        Bundler::PathError,
+        "Your bundle path contains text matching \":\", which is the " \
+        "path separator for your system. Bundler cannot " \
+        "function correctly when the Bundle path contains the " \
+        "system's PATH separator. Please change your " \
+        "bundle path to not match \":\".\nYour current bundle " \
+        "path is '#{Bundler.bundle_path}'."
+      )
+    end
+
+    context "with a jruby path_separator regex", :ruby => "1.9" do
+      # In versions of jruby that supported ruby 1.8, the path separator was the standard File::PATH_SEPARATOR
+      let(:regex) { Regexp.new("(?<!jar:file|jar|file|classpath|uri:classloader|uri|http|https):") }
+      it "does not exit if bundle path is the standard uri path" do
+        allow(Bundler.rubygems).to receive(:path_separator).and_return(regex)
+        allow(Bundler).to receive(:bundle_path) { Pathname.new("uri:classloader:/WEB-INF/gems") }
+        expect { subject.send(:validate_bundle_path) }.not_to raise_error
+      end
+
+      it "exits if bundle path contains another directory" do
+        allow(Bundler.rubygems).to receive(:path_separator).and_return(regex)
+        allow(Bundler).to receive(:bundle_path) {
+          Pathname.new("uri:classloader:/WEB-INF/gems:other/dir")
+        }
+
+        expect { subject.send(:validate_bundle_path) }.to raise_error(
+          Bundler::PathError,
+          "Your bundle path contains text matching " \
+          "/(?<!jar:file|jar|file|classpath|uri:classloader|uri|http|https):/, which is the " \
+          "path separator for your system. Bundler cannot " \
+          "function correctly when the Bundle path contains the " \
+          "system's PATH separator. Please change your " \
+          "bundle path to not match " \
+          "/(?<!jar:file|jar|file|classpath|uri:classloader|uri|http|https):/." \
+          "\nYour current bundle path is '#{Bundler.bundle_path}'."
+        )
+      end
+    end
+
+    context "ENV['PATH'] does not exist" do
+      before { ENV.delete("PATH") }
+
+      it_behaves_like "ENV['PATH'] gets set correctly"
+    end
+
+    context "ENV['PATH'] is empty" do
+      before { ENV["PATH"] = "" }
+
+      it_behaves_like "ENV['PATH'] gets set correctly"
+    end
+
+    context "ENV['PATH'] exists" do
+      before { ENV["PATH"] = "/some_path/bin" }
+
+      it_behaves_like "ENV['PATH'] gets set correctly"
+    end
+
+    context "ENV['PATH'] already contains the bundle bin path" do
+      let(:bundle_path) { "#{Bundler.bundle_path}/bin" }
+
+      before do
+        ENV["PATH"] = bundle_path
+      end
+
+      it_behaves_like "ENV['PATH'] gets set correctly"
+
+      it "ENV['PATH'] should only contain one instance of bundle bin path" do
+        subject.set_bundle_environment
+        paths = (ENV["PATH"]).split(File::PATH_SEPARATOR)
+        expect(paths.count(bundle_path)).to eq(1)
+      end
+    end
+
+    context "ENV['RUBYOPT'] does not exist" do
+      before { ENV.delete("RUBYOPT") }
+
+      it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+    end
+
+    context "ENV['RUBYOPT'] exists without -rbundler/setup" do
+      before { ENV["RUBYOPT"] = "-I/some_app_path/lib" }
+
+      it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+    end
+
+    context "ENV['RUBYOPT'] exists and contains -rbundler/setup" do
+      before { ENV["RUBYOPT"] = "-rbundler/setup" }
+
+      it_behaves_like "ENV['RUBYOPT'] gets set correctly"
+    end
+
+    context "ENV['RUBYLIB'] does not exist" do
+      before { ENV.delete("RUBYLIB") }
+
+      it_behaves_like "ENV['RUBYLIB'] gets set correctly"
+    end
+
+    context "ENV['RUBYLIB'] is empty" do
+      before { ENV["PATH"] = "" }
+
+      it_behaves_like "ENV['RUBYLIB'] gets set correctly"
+    end
+
+    context "ENV['RUBYLIB'] exists" do
+      before { ENV["PATH"] = "/some_path/bin" }
+
+      it_behaves_like "ENV['RUBYLIB'] gets set correctly"
+    end
+
+    context "bundle executable in ENV['BUNDLE_BIN_PATH'] does not exist" do
+      before { ENV["BUNDLE_BIN_PATH"] = "/does/not/exist" }
+      before { Bundler.rubygems.replace_bin_path [], [] }
+
+      it "sets BUNDLE_BIN_PATH to the bundle executable file" do
+        subject.set_bundle_environment
+        bundle_exe = ruby_core? ? "../../../../exe/bundle" : "../../../exe/bundle"
+        expect(ENV["BUNDLE_BIN_PATH"]).to eq(File.expand_path(bundle_exe, __FILE__))
+      end
+    end
+
+    context "ENV['RUBYLIB'] already contains the bundler's ruby version lib path" do
+      let(:ruby_lib_path) { "stubbed_ruby_lib_dir" }
+
+      before do
+        ENV["RUBYLIB"] = ruby_lib_path
+      end
+
+      it_behaves_like "ENV['RUBYLIB'] gets set correctly"
+
+      it "ENV['RUBYLIB'] should only contain one instance of bundler's ruby version lib path" do
+        subject.set_bundle_environment
+        paths = (ENV["RUBYLIB"]).split(File::PATH_SEPARATOR)
+        expect(paths.count(ruby_lib_path)).to eq(1)
+      end
+    end
+  end
+
+  describe "#filesystem_access" do
+    context "system has proper permission access" do
+      let(:file_op_block) { proc {|path| FileUtils.mkdir_p(path) } }
+
+      it "performs the operation in the passed block" do
+        subject.filesystem_access("./test_dir", &file_op_block)
+        expect(Pathname.new("test_dir")).to exist
+      end
+    end
+
+    context "system throws Errno::EACESS" do
+      let(:file_op_block) { proc {|_path| raise Errno::EACCES } }
+
+      it "raises a PermissionError" do
+        expect { subject.filesystem_access("/path", &file_op_block) }.to raise_error(
+          Bundler::PermissionError
+        )
+      end
+    end
+
+    context "system throws Errno::EAGAIN" do
+      let(:file_op_block) { proc {|_path| raise Errno::EAGAIN } }
+
+      it "raises a TemporaryResourceError" do
+        expect { subject.filesystem_access("/path", &file_op_block) }.to raise_error(
+          Bundler::TemporaryResourceError
+        )
+      end
+    end
+
+    context "system throws Errno::EPROTO" do
+      let(:file_op_block) { proc {|_path| raise Errno::EPROTO } }
+
+      it "raises a VirtualProtocolError" do
+        expect { subject.filesystem_access("/path", &file_op_block) }.to raise_error(
+          Bundler::VirtualProtocolError
+        )
+      end
+    end
+
+    context "system throws Errno::ENOTSUP", :ruby => "1.9" do
+      let(:file_op_block) { proc {|_path| raise Errno::ENOTSUP } }
+
+      it "raises a OperationNotSupportedError" do
+        expect { subject.filesystem_access("/path", &file_op_block) }.to raise_error(
+          Bundler::OperationNotSupportedError
+        )
+      end
+    end
+
+    context "system throws Errno::ENOSPC" do
+      let(:file_op_block) { proc {|_path| raise Errno::ENOSPC } }
+
+      it "raises a NoSpaceOnDeviceError" do
+        expect { subject.filesystem_access("/path", &file_op_block) }.to raise_error(
+          Bundler::NoSpaceOnDeviceError
+        )
+      end
+    end
+
+    context "system throws an unhandled SystemCallError" do
+      let(:error) { SystemCallError.new("Shields down", 1337) }
+      let(:file_op_block) { proc {|_path| raise error } }
+
+      it "raises a GenericSystemCallError" do
+        expect { subject.filesystem_access("/path", &file_op_block) }.to raise_error(
+          Bundler::GenericSystemCallError, /error accessing.+underlying.+Shields down/m
+        )
+      end
+    end
+  end
+
+  describe "#const_get_safely" do
+    module TargetNamespace
+      VALID_CONSTANT = 1
+    end
+
+    context "when the namespace does have the requested constant" do
+      it "returns the value of the requested constant" do
+        expect(subject.const_get_safely(:VALID_CONSTANT, TargetNamespace)).to eq(1)
+      end
+    end
+
+    context "when the requested constant is passed as a string" do
+      it "returns the value of the requested constant" do
+        expect(subject.const_get_safely("VALID_CONSTANT", TargetNamespace)).to eq(1)
+      end
+    end
+
+    context "when the namespace does not have the requested constant" do
+      it "returns nil" do
+        expect(subject.const_get_safely("INVALID_CONSTANT", TargetNamespace)).to be_nil
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source/git/git_proxy_spec.rb b/spec/bundler/bundler/source/git/git_proxy_spec.rb
new file mode 100644
index 0000000000..3a29c97461
--- /dev/null
+++ b/spec/bundler/bundler/source/git/git_proxy_spec.rb
@@ -0,0 +1,140 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Source::Git::GitProxy do
+  let(:path) { Pathname("path") }
+  let(:uri) { "https://github.com/bundler/bundler.git" }
+  let(:ref) { "HEAD" }
+  let(:revision) { nil }
+  let(:git_source) { nil }
+  subject { described_class.new(path, uri, ref, revision, git_source) }
+
+  context "with configured credentials" do
+    it "adds username and password to URI" do
+      Bundler.settings.temporary(uri => "u:p")
+      expect(subject).to receive(:git_retry).with(match("https://u:p@github.com/bundler/bundler.git"))
+      subject.checkout
+    end
+
+    it "adds username and password to URI for host" do
+      Bundler.settings.temporary("github.com" => "u:p")
+      expect(subject).to receive(:git_retry).with(match("https://u:p@github.com/bundler/bundler.git"))
+      subject.checkout
+    end
+
+    it "does not add username and password to mismatched URI" do
+      Bundler.settings.temporary("https://u:p@github.com/bundler/bundler-mismatch.git" => "u:p")
+      expect(subject).to receive(:git_retry).with(match(uri))
+      subject.checkout
+    end
+
+    it "keeps original userinfo" do
+      Bundler.settings.temporary("github.com" => "u:p")
+      original = "https://orig:info@github.com/bundler/bundler.git"
+      subject = described_class.new(Pathname("path"), original, "HEAD")
+      expect(subject).to receive(:git_retry).with(match(original))
+      subject.checkout
+    end
+  end
+
+  describe "#version" do
+    context "with a normal version number" do
+      before do
+        expect(subject).to receive(:git).with("--version").
+          and_return("git version 1.2.3")
+      end
+
+      it "returns the git version number" do
+        expect(subject.version).to eq("1.2.3")
+      end
+
+      it "does not raise an error when passed into Gem::Version.create" do
+        expect { Gem::Version.create subject.version }.not_to raise_error
+      end
+    end
+
+    context "with a OSX version number" do
+      before do
+        expect(subject).to receive(:git).with("--version").
+          and_return("git version 1.2.3 (Apple Git-BS)")
+      end
+
+      it "strips out OSX specific additions in the version string" do
+        expect(subject.version).to eq("1.2.3")
+      end
+
+      it "does not raise an error when passed into Gem::Version.create" do
+        expect { Gem::Version.create subject.version }.not_to raise_error
+      end
+    end
+
+    context "with a msysgit version number" do
+      before do
+        expect(subject).to receive(:git).with("--version").
+          and_return("git version 1.2.3.msysgit.0")
+      end
+
+      it "strips out msysgit specific additions in the version string" do
+        expect(subject.version).to eq("1.2.3")
+      end
+
+      it "does not raise an error when passed into Gem::Version.create" do
+        expect { Gem::Version.create subject.version }.not_to raise_error
+      end
+    end
+  end
+
+  describe "#full_version" do
+    context "with a normal version number" do
+      before do
+        expect(subject).to receive(:git).with("--version").
+          and_return("git version 1.2.3")
+      end
+
+      it "returns the git version number" do
+        expect(subject.full_version).to eq("1.2.3")
+      end
+    end
+
+    context "with a OSX version number" do
+      before do
+        expect(subject).to receive(:git).with("--version").
+          and_return("git version 1.2.3 (Apple Git-BS)")
+      end
+
+      it "does not strip out OSX specific additions in the version string" do
+        expect(subject.full_version).to eq("1.2.3 (Apple Git-BS)")
+      end
+    end
+
+    context "with a msysgit version number" do
+      before do
+        expect(subject).to receive(:git).with("--version").
+          and_return("git version 1.2.3.msysgit.0")
+      end
+
+      it "does not strip out msysgit specific additions in the version string" do
+        expect(subject.full_version).to eq("1.2.3.msysgit.0")
+      end
+    end
+  end
+
+  describe "#copy_to" do
+    let(:destination) { tmpdir("copy_to_path") }
+    let(:submodules) { false }
+
+    context "when given a SHA as a revision" do
+      let(:revision) { "abcd" * 10 }
+
+      it "fails gracefully when resetting to the revision fails" do
+        expect(subject).to receive(:git_retry).with(start_with("clone ")) { destination.mkpath }
+        expect(subject).to receive(:git_retry).with(start_with("fetch "))
+        expect(subject).to receive(:git).with("reset --hard #{revision}").and_raise(Bundler::Source::Git::GitCommandError, "command")
+        expect(subject).not_to receive(:git)
+
+        expect { subject.copy_to(destination, submodules) }.
+          to raise_error(Bundler::Source::Git::MissingGitRevisionError,
+            "Revision #{revision} does not exist in the repository #{uri}. Maybe you misspelled it?")
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source/git_spec.rb b/spec/bundler/bundler/source/git_spec.rb
new file mode 100644
index 0000000000..f7475a35aa
--- /dev/null
+++ b/spec/bundler/bundler/source/git_spec.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Source::Git do
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new("root") }
+  end
+
+  let(:uri) { "https://github.com/foo/bar.git" }
+  let(:options) do
+    { "uri" => uri }
+  end
+
+  subject { described_class.new(options) }
+
+  describe "#to_s" do
+    it "returns a description" do
+      expect(subject.to_s).to eq "https://github.com/foo/bar.git (at master)"
+    end
+
+    context "when the URI contains credentials" do
+      let(:uri) { "https://my-secret-token:x-oauth-basic@github.com/foo/bar.git" }
+
+      it "filters credentials" do
+        expect(subject.to_s).to eq "https://x-oauth-basic@github.com/foo/bar.git (at master)"
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source/path_spec.rb b/spec/bundler/bundler/source/path_spec.rb
new file mode 100644
index 0000000000..1d13e03ec1
--- /dev/null
+++ b/spec/bundler/bundler/source/path_spec.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Source::Path do
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new("root") }
+  end
+
+  describe "#eql?" do
+    subject { described_class.new("path" => "gems/a") }
+
+    context "with two equivalent relative paths from different roots" do
+      let(:a_gem_opts) { { "path" => "../gems/a", "root_path" => Bundler.root.join("nested") } }
+      let(:a_gem)      { described_class.new a_gem_opts }
+
+      it "returns true" do
+        expect(subject).to eq a_gem
+      end
+    end
+
+    context "with the same (but not equivalent) relative path from different roots" do
+      subject { described_class.new("path" => "gems/a") }
+
+      let(:a_gem_opts) { { "path" => "gems/a", "root_path" => Bundler.root.join("nested") } }
+      let(:a_gem)      { described_class.new a_gem_opts }
+
+      it "returns false" do
+        expect(subject).to_not eq a_gem
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source/rubygems/remote_spec.rb b/spec/bundler/bundler/source/rubygems/remote_spec.rb
new file mode 100644
index 0000000000..9a7ab42128
--- /dev/null
+++ b/spec/bundler/bundler/source/rubygems/remote_spec.rb
@@ -0,0 +1,162 @@
+# frozen_string_literal: true
+
+require "bundler/source/rubygems/remote"
+
+RSpec.describe Bundler::Source::Rubygems::Remote do
+  def remote(uri)
+    Bundler::Source::Rubygems::Remote.new(uri)
+  end
+
+  before do
+    allow(Digest(:MD5)).to receive(:hexdigest).with(duck_type(:to_s)) {|string| "MD5HEX(#{string})" }
+  end
+
+  let(:uri_no_auth) { URI("https://gems.example.com") }
+  let(:uri_with_auth) { URI("https://#{credentials}@gems.example.com") }
+  let(:credentials) { "username:password" }
+
+  context "when the original URI has no credentials" do
+    describe "#uri" do
+      it "returns the original URI" do
+        expect(remote(uri_no_auth).uri).to eq(uri_no_auth)
+      end
+
+      it "applies configured credentials" do
+        Bundler.settings.temporary(uri_no_auth.to_s => credentials)
+        expect(remote(uri_no_auth).uri).to eq(uri_with_auth)
+      end
+    end
+
+    describe "#anonymized_uri" do
+      it "returns the original URI" do
+        expect(remote(uri_no_auth).anonymized_uri).to eq(uri_no_auth)
+      end
+
+      it "does not apply given credentials" do
+        Bundler.settings.temporary(uri_no_auth.to_s => credentials)
+        expect(remote(uri_no_auth).anonymized_uri).to eq(uri_no_auth)
+      end
+    end
+
+    describe "#cache_slug" do
+      it "returns the correct slug" do
+        expect(remote(uri_no_auth).cache_slug).to eq("gems.example.com.443.MD5HEX(gems.example.com.443./)")
+      end
+
+      it "only applies the given user" do
+        Bundler.settings.temporary(uri_no_auth.to_s => credentials)
+        expect(remote(uri_no_auth).cache_slug).to eq("gems.example.com.username.443.MD5HEX(gems.example.com.username.443./)")
+      end
+    end
+  end
+
+  context "when the original URI has a username and password" do
+    describe "#uri" do
+      it "returns the original URI" do
+        expect(remote(uri_with_auth).uri).to eq(uri_with_auth)
+      end
+
+      it "does not apply configured credentials" do
+        Bundler.settings.temporary(uri_no_auth.to_s => "other:stuff")
+        expect(remote(uri_with_auth).uri).to eq(uri_with_auth)
+      end
+    end
+
+    describe "#anonymized_uri" do
+      it "returns the URI without username and password" do
+        expect(remote(uri_with_auth).anonymized_uri).to eq(uri_no_auth)
+      end
+
+      it "does not apply given credentials" do
+        Bundler.settings.temporary(uri_no_auth.to_s => "other:stuff")
+        expect(remote(uri_with_auth).anonymized_uri).to eq(uri_no_auth)
+      end
+    end
+
+    describe "#cache_slug" do
+      it "returns the correct slug" do
+        expect(remote(uri_with_auth).cache_slug).to eq("gems.example.com.username.443.MD5HEX(gems.example.com.username.443./)")
+      end
+
+      it "does not apply given credentials" do
+        Bundler.settings.temporary(uri_with_auth.to_s => credentials)
+        expect(remote(uri_with_auth).cache_slug).to eq("gems.example.com.username.443.MD5HEX(gems.example.com.username.443./)")
+      end
+    end
+  end
+
+  context "when the original URI has only a username" do
+    let(:uri) { URI("https://SeCrEt-ToKeN@gem.fury.io/me/") }
+
+    describe "#anonymized_uri" do
+      it "returns the URI without username and password" do
+        expect(remote(uri).anonymized_uri).to eq(URI("https://gem.fury.io/me/"))
+      end
+    end
+
+    describe "#cache_slug" do
+      it "returns the correct slug" do
+        expect(remote(uri).cache_slug).to eq("gem.fury.io.SeCrEt-ToKeN.443.MD5HEX(gem.fury.io.SeCrEt-ToKeN.443./me/)")
+      end
+    end
+  end
+
+  context "when a mirror with inline credentials is configured for the URI" do
+    let(:uri) { URI("https://rubygems.org/") }
+    let(:mirror_uri_with_auth) { URI("https://username:password@rubygems-mirror.org/") }
+    let(:mirror_uri_no_auth) { URI("https://rubygems-mirror.org/") }
+
+    before { Bundler.settings.set_local("mirror.https://rubygems.org/", mirror_uri_with_auth.to_s) }
+
+    specify "#uri returns the mirror URI with credentials" do
+      expect(remote(uri).uri).to eq(mirror_uri_with_auth)
+    end
+
+    specify "#anonymized_uri returns the mirror URI without credentials" do
+      expect(remote(uri).anonymized_uri).to eq(mirror_uri_no_auth)
+    end
+
+    specify "#original_uri returns the original source" do
+      expect(remote(uri).original_uri).to eq(uri)
+    end
+
+    specify "#cache_slug returns the correct slug" do
+      expect(remote(uri).cache_slug).to eq("rubygems.org.443.MD5HEX(rubygems.org.443./)")
+    end
+  end
+
+  context "when a mirror with configured credentials is configured for the URI" do
+    let(:uri) { URI("https://rubygems.org/") }
+    let(:mirror_uri_with_auth) { URI("https://#{credentials}@rubygems-mirror.org/") }
+    let(:mirror_uri_no_auth) { URI("https://rubygems-mirror.org/") }
+
+    before do
+      Bundler.settings.temporary("mirror.https://rubygems.org/" => mirror_uri_no_auth.to_s)
+      Bundler.settings.temporary(mirror_uri_no_auth.to_s => credentials)
+    end
+
+    specify "#uri returns the mirror URI with credentials" do
+      expect(remote(uri).uri).to eq(mirror_uri_with_auth)
+    end
+
+    specify "#anonymized_uri returns the mirror URI without credentials" do
+      expect(remote(uri).anonymized_uri).to eq(mirror_uri_no_auth)
+    end
+
+    specify "#original_uri returns the original source" do
+      expect(remote(uri).original_uri).to eq(uri)
+    end
+
+    specify "#cache_slug returns the original source" do
+      expect(remote(uri).cache_slug).to eq("rubygems.org.443.MD5HEX(rubygems.org.443./)")
+    end
+  end
+
+  context "when there is no mirror set" do
+    describe "#original_uri" do
+      it "is not set" do
+        expect(remote(uri_no_auth).original_uri).to be_nil
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source/rubygems_spec.rb b/spec/bundler/bundler/source/rubygems_spec.rb
new file mode 100644
index 0000000000..7c457a7265
--- /dev/null
+++ b/spec/bundler/bundler/source/rubygems_spec.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Source::Rubygems do
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new("root") }
+  end
+
+  describe "caches" do
+    it "includes Bundler.app_cache" do
+      expect(subject.caches).to include(Bundler.app_cache)
+    end
+
+    it "includes GEM_PATH entries" do
+      Gem.path.each do |path|
+        expect(subject.caches).to include(File.expand_path("#{path}/cache"))
+      end
+    end
+
+    it "is an array of strings or pathnames" do
+      subject.caches.each do |cache|
+        expect([String, Pathname]).to include(cache.class)
+      end
+    end
+  end
+
+  describe "#add_remote" do
+    context "when the source is an HTTP(s) URI with no host" do
+      it "raises error" do
+        expect { subject.add_remote("https:rubygems.org") }.to raise_error(ArgumentError)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source_list_spec.rb b/spec/bundler/bundler/source_list_spec.rb
new file mode 100644
index 0000000000..ce3353012c
--- /dev/null
+++ b/spec/bundler/bundler/source_list_spec.rb
@@ -0,0 +1,463 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::SourceList do
+  before do
+    allow(Bundler).to receive(:root) { Pathname.new "./tmp/bundled_app" }
+
+    stub_const "ASourcePlugin", Class.new(Bundler::Plugin::API)
+    ASourcePlugin.source "new_source"
+    allow(Bundler::Plugin).to receive(:source?).with("new_source").and_return(true)
+  end
+
+  subject(:source_list) { Bundler::SourceList.new }
+
+  let(:rubygems_aggregate) { Bundler::Source::Rubygems.new }
+  let(:metadata_source) { Bundler::Source::Metadata.new }
+
+  describe "adding sources" do
+    before do
+      source_list.add_path_source("path" => "/existing/path/to/gem")
+      source_list.add_git_source("uri" => "git://existing-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://existing-rubygems.org"])
+      source_list.add_plugin_source("new_source", "uri" => "https://some.url/a")
+    end
+
+    describe "#add_path_source" do
+      before do
+        @duplicate = source_list.add_path_source("path" => "/path/to/gem")
+        @new_source = source_list.add_path_source("path" => "/path/to/gem")
+      end
+
+      it "returns the new path source" do
+        expect(@new_source).to be_instance_of(Bundler::Source::Path)
+      end
+
+      it "passes the provided options to the new source" do
+        expect(@new_source.options).to eq("path" => "/path/to/gem")
+      end
+
+      it "adds the source to the beginning of path_sources" do
+        expect(source_list.path_sources.first).to equal(@new_source)
+      end
+
+      it "removes existing duplicates" do
+        expect(source_list.path_sources).not_to include equal(@duplicate)
+      end
+    end
+
+    describe "#add_git_source" do
+      before do
+        @duplicate = source_list.add_git_source("uri" => "git://host/path.git")
+        @new_source = source_list.add_git_source("uri" => "git://host/path.git")
+      end
+
+      it "returns the new git source" do
+        expect(@new_source).to be_instance_of(Bundler::Source::Git)
+      end
+
+      it "passes the provided options to the new source" do
+        @new_source = source_list.add_git_source("uri" => "git://host/path.git")
+        expect(@new_source.options).to eq("uri" => "git://host/path.git")
+      end
+
+      it "adds the source to the beginning of git_sources" do
+        @new_source = source_list.add_git_source("uri" => "git://host/path.git")
+        expect(source_list.git_sources.first).to equal(@new_source)
+      end
+
+      it "removes existing duplicates" do
+        @duplicate = source_list.add_git_source("uri" => "git://host/path.git")
+        @new_source = source_list.add_git_source("uri" => "git://host/path.git")
+        expect(source_list.git_sources).not_to include equal(@duplicate)
+      end
+
+      context "with the git: protocol" do
+        let(:msg) do
+          "The git source `git://existing-git.org/path.git` " \
+          "uses the `git` protocol, which transmits data without encryption. " \
+          "Disable this warning with `bundle config git.allow_insecure true`, " \
+          "or switch to the `https` protocol to keep your data secure."
+        end
+
+        it "warns about git protocols" do
+          expect(Bundler.ui).to receive(:warn).with(msg)
+          source_list.add_git_source("uri" => "git://existing-git.org/path.git")
+        end
+
+        it "ignores git protocols on request" do
+          Bundler.settings.temporary(:"git.allow_insecure" => true)
+          expect(Bundler.ui).to_not receive(:warn).with(msg)
+          source_list.add_git_source("uri" => "git://existing-git.org/path.git")
+        end
+      end
+    end
+
+    describe "#add_rubygems_source" do
+      before do
+        @duplicate = source_list.add_rubygems_source("remotes" => ["https://rubygems.org/"])
+        @new_source = source_list.add_rubygems_source("remotes" => ["https://rubygems.org/"])
+      end
+
+      it "returns the new rubygems source" do
+        expect(@new_source).to be_instance_of(Bundler::Source::Rubygems)
+      end
+
+      it "passes the provided options to the new source" do
+        expect(@new_source.options).to eq("remotes" => ["https://rubygems.org/"])
+      end
+
+      it "adds the source to the beginning of rubygems_sources" do
+        expect(source_list.rubygems_sources.first).to equal(@new_source)
+      end
+
+      it "removes duplicates" do
+        expect(source_list.rubygems_sources).not_to include equal(@duplicate)
+      end
+    end
+
+    describe "#add_rubygems_remote", :bundler => "< 2" do
+      let!(:returned_source) { source_list.add_rubygems_remote("https://rubygems.org/") }
+
+      it "returns the aggregate rubygems source" do
+        expect(returned_source).to be_instance_of(Bundler::Source::Rubygems)
+      end
+
+      it "adds the provided remote to the beginning of the aggregate source" do
+        source_list.add_rubygems_remote("https://othersource.org")
+        expect(returned_source.remotes).to eq [
+          URI("https://othersource.org/"),
+          URI("https://rubygems.org/"),
+        ]
+      end
+    end
+
+    describe "#add_plugin_source" do
+      before do
+        @duplicate = source_list.add_plugin_source("new_source", "uri" => "http://host/path.")
+        @new_source = source_list.add_plugin_source("new_source", "uri" => "http://host/path.")
+      end
+
+      it "returns the new plugin source" do
+        expect(@new_source).to be_a(Bundler::Plugin::API::Source)
+      end
+
+      it "passes the provided options to the new source" do
+        expect(@new_source.options).to eq("uri" => "http://host/path.")
+      end
+
+      it "adds the source to the beginning of git_sources" do
+        expect(source_list.plugin_sources.first).to equal(@new_source)
+      end
+
+      it "removes existing duplicates" do
+        expect(source_list.plugin_sources).not_to include equal(@duplicate)
+      end
+    end
+  end
+
+  describe "#all_sources" do
+    it "includes the aggregate rubygems source when rubygems sources have been added" do
+      source_list.add_git_source("uri" => "git://host/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://rubygems.org"])
+      source_list.add_path_source("path" => "/path/to/gem")
+      source_list.add_plugin_source("new_source", "uri" => "https://some.url/a")
+
+      expect(source_list.all_sources).to include rubygems_aggregate
+    end
+
+    it "includes the aggregate rubygems source when no rubygems sources have been added" do
+      source_list.add_git_source("uri" => "git://host/path.git")
+      source_list.add_path_source("path" => "/path/to/gem")
+      source_list.add_plugin_source("new_source", "uri" => "https://some.url/a")
+
+      expect(source_list.all_sources).to include rubygems_aggregate
+    end
+
+    it "returns sources of the same type in the reverse order that they were added" do
+      source_list.add_git_source("uri" => "git://third-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://fifth-rubygems.org"])
+      source_list.add_path_source("path" => "/third/path/to/gem")
+      source_list.add_plugin_source("new_source", "uri" => "https://some.url/b")
+      source_list.add_rubygems_source("remotes" => ["https://fourth-rubygems.org"])
+      source_list.add_path_source("path" => "/second/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://third-rubygems.org"])
+      source_list.add_plugin_source("new_source", "uri" => "https://some.o.url/")
+      source_list.add_git_source("uri" => "git://second-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://second-rubygems.org"])
+      source_list.add_path_source("path" => "/first/path/to/gem")
+      source_list.add_plugin_source("new_source", "uri" => "https://some.url/c")
+      source_list.add_rubygems_source("remotes" => ["https://first-rubygems.org"])
+      source_list.add_git_source("uri" => "git://first-git.org/path.git")
+
+      expect(source_list.all_sources).to eq [
+        Bundler::Source::Path.new("path" => "/first/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/second/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/third/path/to/gem"),
+        Bundler::Source::Git.new("uri" => "git://first-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://second-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://third-git.org/path.git"),
+        ASourcePlugin.new("uri" => "https://some.url/c"),
+        ASourcePlugin.new("uri" => "https://some.o.url/"),
+        ASourcePlugin.new("uri" => "https://some.url/b"),
+        Bundler::Source::Rubygems.new("remotes" => ["https://first-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://second-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://third-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://fourth-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://fifth-rubygems.org"]),
+        rubygems_aggregate,
+        metadata_source,
+      ]
+    end
+  end
+
+  describe "#path_sources" do
+    it "returns an empty array when no path sources have been added" do
+      source_list.add_rubygems_remote("https://rubygems.org")
+      source_list.add_git_source("uri" => "git://host/path.git")
+      expect(source_list.path_sources).to be_empty
+    end
+
+    it "returns path sources in the reverse order that they were added" do
+      source_list.add_git_source("uri" => "git://third-git.org/path.git")
+      source_list.add_rubygems_remote("https://fifth-rubygems.org")
+      source_list.add_path_source("path" => "/third/path/to/gem")
+      source_list.add_rubygems_remote("https://fourth-rubygems.org")
+      source_list.add_path_source("path" => "/second/path/to/gem")
+      source_list.add_rubygems_remote("https://third-rubygems.org")
+      source_list.add_git_source("uri" => "git://second-git.org/path.git")
+      source_list.add_rubygems_remote("https://second-rubygems.org")
+      source_list.add_path_source("path" => "/first/path/to/gem")
+      source_list.add_rubygems_remote("https://first-rubygems.org")
+      source_list.add_git_source("uri" => "git://first-git.org/path.git")
+
+      expect(source_list.path_sources).to eq [
+        Bundler::Source::Path.new("path" => "/first/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/second/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/third/path/to/gem"),
+      ]
+    end
+  end
+
+  describe "#git_sources" do
+    it "returns an empty array when no git sources have been added" do
+      source_list.add_rubygems_remote("https://rubygems.org")
+      source_list.add_path_source("path" => "/path/to/gem")
+
+      expect(source_list.git_sources).to be_empty
+    end
+
+    it "returns git sources in the reverse order that they were added" do
+      source_list.add_git_source("uri" => "git://third-git.org/path.git")
+      source_list.add_rubygems_remote("https://fifth-rubygems.org")
+      source_list.add_path_source("path" => "/third/path/to/gem")
+      source_list.add_rubygems_remote("https://fourth-rubygems.org")
+      source_list.add_path_source("path" => "/second/path/to/gem")
+      source_list.add_rubygems_remote("https://third-rubygems.org")
+      source_list.add_git_source("uri" => "git://second-git.org/path.git")
+      source_list.add_rubygems_remote("https://second-rubygems.org")
+      source_list.add_path_source("path" => "/first/path/to/gem")
+      source_list.add_rubygems_remote("https://first-rubygems.org")
+      source_list.add_git_source("uri" => "git://first-git.org/path.git")
+
+      expect(source_list.git_sources).to eq [
+        Bundler::Source::Git.new("uri" => "git://first-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://second-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://third-git.org/path.git"),
+      ]
+    end
+  end
+
+  describe "#plugin_sources" do
+    it "returns an empty array when no plugin sources have been added" do
+      source_list.add_rubygems_remote("https://rubygems.org")
+      source_list.add_path_source("path" => "/path/to/gem")
+
+      expect(source_list.plugin_sources).to be_empty
+    end
+
+    it "returns plugin sources in the reverse order that they were added" do
+      source_list.add_plugin_source("new_source", "uri" => "https://third-git.org/path.git")
+      source_list.add_git_source("https://new-git.org")
+      source_list.add_path_source("path" => "/third/path/to/gem")
+      source_list.add_rubygems_remote("https://fourth-rubygems.org")
+      source_list.add_path_source("path" => "/second/path/to/gem")
+      source_list.add_rubygems_remote("https://third-rubygems.org")
+      source_list.add_plugin_source("new_source", "uri" => "git://second-git.org/path.git")
+      source_list.add_rubygems_remote("https://second-rubygems.org")
+      source_list.add_path_source("path" => "/first/path/to/gem")
+      source_list.add_rubygems_remote("https://first-rubygems.org")
+      source_list.add_plugin_source("new_source", "uri" => "git://first-git.org/path.git")
+
+      expect(source_list.plugin_sources).to eq [
+        ASourcePlugin.new("uri" => "git://first-git.org/path.git"),
+        ASourcePlugin.new("uri" => "git://second-git.org/path.git"),
+        ASourcePlugin.new("uri" => "https://third-git.org/path.git"),
+      ]
+    end
+  end
+
+  describe "#rubygems_sources" do
+    it "includes the aggregate rubygems source when rubygems sources have been added" do
+      source_list.add_git_source("uri" => "git://host/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://rubygems.org"])
+      source_list.add_path_source("path" => "/path/to/gem")
+
+      expect(source_list.rubygems_sources).to include rubygems_aggregate
+    end
+
+    it "returns only the aggregate rubygems source when no rubygems sources have been added" do
+      source_list.add_git_source("uri" => "git://host/path.git")
+      source_list.add_path_source("path" => "/path/to/gem")
+
+      expect(source_list.rubygems_sources).to eq [rubygems_aggregate]
+    end
+
+    it "returns rubygems sources in the reverse order that they were added" do
+      source_list.add_git_source("uri" => "git://third-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://fifth-rubygems.org"])
+      source_list.add_path_source("path" => "/third/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://fourth-rubygems.org"])
+      source_list.add_path_source("path" => "/second/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://third-rubygems.org"])
+      source_list.add_git_source("uri" => "git://second-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://second-rubygems.org"])
+      source_list.add_path_source("path" => "/first/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://first-rubygems.org"])
+      source_list.add_git_source("uri" => "git://first-git.org/path.git")
+
+      expect(source_list.rubygems_sources).to eq [
+        Bundler::Source::Rubygems.new("remotes" => ["https://first-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://second-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://third-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://fourth-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://fifth-rubygems.org"]),
+        rubygems_aggregate,
+      ]
+    end
+  end
+
+  describe "#get" do
+    context "when it includes an equal source" do
+      let(:rubygems_source) { Bundler::Source::Rubygems.new("remotes" => ["https://rubygems.org"]) }
+      before { @equal_source = source_list.add_rubygems_remote("https://rubygems.org") }
+
+      it "returns the equal source" do
+        expect(source_list.get(rubygems_source)).to be @equal_source
+      end
+    end
+
+    context "when it does not include an equal source" do
+      let(:path_source) { Bundler::Source::Path.new("path" => "/path/to/gem") }
+
+      it "returns nil" do
+        expect(source_list.get(path_source)).to be_nil
+      end
+    end
+  end
+
+  describe "#lock_sources" do
+    before do
+      source_list.add_git_source("uri" => "git://third-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://duplicate-rubygems.org"])
+      source_list.add_plugin_source("new_source", "uri" => "https://third-bar.org/foo")
+      source_list.add_path_source("path" => "/third/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://third-rubygems.org"])
+      source_list.add_path_source("path" => "/second/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://second-rubygems.org"])
+      source_list.add_git_source("uri" => "git://second-git.org/path.git")
+      source_list.add_rubygems_source("remotes" => ["https://first-rubygems.org"])
+      source_list.add_plugin_source("new_source", "uri" => "https://second-plugin.org/random")
+      source_list.add_path_source("path" => "/first/path/to/gem")
+      source_list.add_rubygems_source("remotes" => ["https://duplicate-rubygems.org"])
+      source_list.add_git_source("uri" => "git://first-git.org/path.git")
+    end
+
+    it "combines the rubygems sources into a single instance, removing duplicate remotes from the end", :bundler => "< 2" do
+      expect(source_list.lock_sources).to eq [
+        Bundler::Source::Git.new("uri" => "git://first-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://second-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://third-git.org/path.git"),
+        ASourcePlugin.new("uri" => "https://second-plugin.org/random"),
+        ASourcePlugin.new("uri" => "https://third-bar.org/foo"),
+        Bundler::Source::Path.new("path" => "/first/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/second/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/third/path/to/gem"),
+        Bundler::Source::Rubygems.new("remotes" => [
+          "https://duplicate-rubygems.org",
+          "https://first-rubygems.org",
+          "https://second-rubygems.org",
+          "https://third-rubygems.org",
+        ]),
+      ]
+    end
+
+    it "returns all sources, without combining rubygems sources", :bundler => "2" do
+      expect(source_list.lock_sources).to eq [
+        Bundler::Source::Rubygems.new,
+        Bundler::Source::Rubygems.new("remotes" => ["https://duplicate-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://first-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://second-rubygems.org"]),
+        Bundler::Source::Rubygems.new("remotes" => ["https://third-rubygems.org"]),
+        Bundler::Source::Git.new("uri" => "git://first-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://second-git.org/path.git"),
+        Bundler::Source::Git.new("uri" => "git://third-git.org/path.git"),
+        Bundler::Source::Path.new("path" => "/first/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/second/path/to/gem"),
+        Bundler::Source::Path.new("path" => "/third/path/to/gem"),
+        ASourcePlugin.new("uri" => "https://second-plugin.org/random"),
+        ASourcePlugin.new("uri" => "https://third-bar.org/foo"),
+      ]
+    end
+  end
+
+  describe "replace_sources!" do
+    let(:existing_locked_source) { Bundler::Source::Path.new("path" => "/existing/path") }
+    let(:removed_locked_source)  { Bundler::Source::Path.new("path" => "/removed/path") }
+
+    let(:locked_sources) { [existing_locked_source, removed_locked_source] }
+
+    before do
+      @existing_source = source_list.add_path_source("path" => "/existing/path")
+      @new_source = source_list.add_path_source("path" => "/new/path")
+      source_list.replace_sources!(locked_sources)
+    end
+
+    it "maintains the order and number of sources" do
+      expect(source_list.path_sources).to eq [@new_source, @existing_source]
+    end
+
+    it "retains the same instance of the new source" do
+      expect(source_list.path_sources[0]).to be @new_source
+    end
+
+    it "replaces the instance of the existing source" do
+      expect(source_list.path_sources[1]).to be existing_locked_source
+    end
+  end
+
+  describe "#cached!" do
+    let(:rubygems_source) { source_list.add_rubygems_source("remotes" => ["https://rubygems.org"]) }
+    let(:git_source)      { source_list.add_git_source("uri" => "git://host/path.git") }
+    let(:path_source)     { source_list.add_path_source("path" => "/path/to/gem") }
+
+    it "calls #cached! on all the sources" do
+      expect(rubygems_source).to receive(:cached!)
+      expect(git_source).to receive(:cached!)
+      expect(path_source).to receive(:cached!)
+      source_list.cached!
+    end
+  end
+
+  describe "#remote!" do
+    let(:rubygems_source) { source_list.add_rubygems_source("remotes" => ["https://rubygems.org"]) }
+    let(:git_source)      { source_list.add_git_source("uri" => "git://host/path.git") }
+    let(:path_source)     { source_list.add_path_source("path" => "/path/to/gem") }
+
+    it "calls #remote! on all the sources" do
+      expect(rubygems_source).to receive(:remote!)
+      expect(git_source).to receive(:remote!)
+      expect(path_source).to receive(:remote!)
+      source_list.remote!
+    end
+  end
+end
diff --git a/spec/bundler/bundler/source_spec.rb b/spec/bundler/bundler/source_spec.rb
new file mode 100644
index 0000000000..9ef8e7e50f
--- /dev/null
+++ b/spec/bundler/bundler/source_spec.rb
@@ -0,0 +1,154 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::Source do
+  class ExampleSource < Bundler::Source
+  end
+
+  subject { ExampleSource.new }
+
+  describe "#unmet_deps" do
+    let(:specs) { double(:specs) }
+    let(:unmet_dependency_names) { double(:unmet_dependency_names) }
+
+    before do
+      allow(subject).to receive(:specs).and_return(specs)
+      allow(specs).to receive(:unmet_dependency_names).and_return(unmet_dependency_names)
+    end
+
+    it "should return the names of unmet dependencies" do
+      expect(subject.unmet_deps).to eq(unmet_dependency_names)
+    end
+  end
+
+  describe "#version_message" do
+    let(:spec) { double(:spec, :name => "nokogiri", :version => ">= 1.6", :platform => rb) }
+
+    shared_examples_for "the lockfile specs are not relevant" do
+      it "should return a string with the spec name and version" do
+        expect(subject.version_message(spec)).to eq("nokogiri >= 1.6")
+      end
+    end
+
+    context "when there are locked gems" do
+      let(:locked_gems) { double(:locked_gems) }
+
+      before { allow(Bundler).to receive(:locked_gems).and_return(locked_gems) }
+
+      context "that contain the relevant gem spec" do
+        before do
+          specs = double(:specs)
+          allow(locked_gems).to receive(:specs).and_return(specs)
+          allow(specs).to receive(:find).and_return(locked_gem)
+        end
+
+        context "without a version" do
+          let(:locked_gem) { double(:locked_gem, :name => "nokogiri", :version => nil) }
+
+          it_behaves_like "the lockfile specs are not relevant"
+        end
+
+        context "with the same version" do
+          let(:locked_gem) { double(:locked_gem, :name => "nokogiri", :version => ">= 1.6") }
+
+          it_behaves_like "the lockfile specs are not relevant"
+        end
+
+        context "with a different version" do
+          let(:locked_gem) { double(:locked_gem, :name => "nokogiri", :version => "< 1.5") }
+
+          context "with color" do
+            before { Bundler.ui = Bundler::UI::Shell.new }
+
+            it "should return a string with the spec name and version and locked spec version" do
+              expect(subject.version_message(spec)).to eq("nokogiri >= 1.6\e[32m (was < 1.5)\e[0m")
+            end
+          end
+
+          context "without color" do
+            it "should return a string with the spec name and version and locked spec version" do
+              expect(subject.version_message(spec)).to eq("nokogiri >= 1.6 (was < 1.5)")
+            end
+          end
+        end
+
+        context "with a more recent version" do
+          let(:spec) { double(:spec, :name => "nokogiri", :version => "1.6.1", :platform => rb) }
+          let(:locked_gem) { double(:locked_gem, :name => "nokogiri", :version => "1.7.0") }
+
+          context "with color" do
+            before { Bundler.ui = Bundler::UI::Shell.new }
+
+            it "should return a string with the locked spec version in yellow" do
+              expect(subject.version_message(spec)).to eq("nokogiri 1.6.1\e[33m (was 1.7.0)\e[0m")
+            end
+          end
+        end
+
+        context "with an older version" do
+          let(:spec) { double(:spec, :name => "nokogiri", :version => "1.7.1", :platform => rb) }
+          let(:locked_gem) { double(:locked_gem, :name => "nokogiri", :version => "1.7.0") }
+
+          context "with color" do
+            before { Bundler.ui = Bundler::UI::Shell.new }
+
+            it "should return a string with the locked spec version in green" do
+              expect(subject.version_message(spec)).to eq("nokogiri 1.7.1\e[32m (was 1.7.0)\e[0m")
+            end
+          end
+        end
+      end
+
+      context "that do not contain the relevant gem spec" do
+        before do
+          specs = double(:specs)
+          allow(locked_gems).to receive(:specs).and_return(specs)
+          allow(specs).to receive(:find).and_return(nil)
+        end
+
+        it_behaves_like "the lockfile specs are not relevant"
+      end
+    end
+
+    context "when there are no locked gems" do
+      before { allow(Bundler).to receive(:locked_gems).and_return(nil) }
+
+      it_behaves_like "the lockfile specs are not relevant"
+    end
+  end
+
+  describe "#can_lock?" do
+    context "when the passed spec's source is equivalent" do
+      let(:spec) { double(:spec, :source => subject) }
+
+      it "should return true" do
+        expect(subject.can_lock?(spec)).to be_truthy
+      end
+    end
+
+    context "when the passed spec's source is not equivalent" do
+      let(:spec) { double(:spec, :source => double(:other_source)) }
+
+      it "should return false" do
+        expect(subject.can_lock?(spec)).to be_falsey
+      end
+    end
+  end
+
+  describe "#include?" do
+    context "when the passed source is equivalent" do
+      let(:source) { subject }
+
+      it "should return true" do
+        expect(subject).to include(source)
+      end
+    end
+
+    context "when the passed source is not equivalent" do
+      let(:source) { double(:source) }
+
+      it "should return false" do
+        expect(subject).to_not include(source)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/spec_set_spec.rb b/spec/bundler/bundler/spec_set_spec.rb
new file mode 100644
index 0000000000..6fedd38b50
--- /dev/null
+++ b/spec/bundler/bundler/spec_set_spec.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::SpecSet do
+  let(:specs) do
+    [
+      build_spec("a", "1.0"),
+      build_spec("b", "1.0"),
+      build_spec("c", "1.1") do |s|
+        s.dep "a", "< 2.0"
+        s.dep "e", "> 0"
+      end,
+      build_spec("d", "2.0") do |s|
+        s.dep "a", "1.0"
+        s.dep "c", "~> 1.0"
+      end,
+      build_spec("e", "1.0.0.pre.1"),
+    ].flatten
+  end
+
+  subject { described_class.new(specs) }
+
+  context "enumerable methods" do
+    it "has a length" do
+      expect(subject.length).to eq(5)
+    end
+
+    it "has a size" do
+      expect(subject.size).to eq(5)
+    end
+  end
+
+  describe "#find_by_name_and_platform" do
+    let(:platform) { Gem::Platform.new("universal-darwin-64") }
+    let(:platform_spec) { build_spec("b", "2.0", platform).first }
+    let(:specs) do
+      [
+        build_spec("a", "1.0"),
+        platform_spec,
+      ].flatten
+    end
+
+    it "finds spec with given name and platform" do
+      spec = described_class.new(specs).find_by_name_and_platform("b", platform)
+      expect(spec).to eq platform_spec
+    end
+  end
+
+  describe "#merge" do
+    let(:other_specs) do
+      [
+        build_spec("f", "1.0"),
+        build_spec("g", "2.0"),
+      ].flatten
+    end
+
+    let(:other_spec_set) { described_class.new(other_specs) }
+
+    it "merges the items in each gemspec" do
+      new_spec_set = subject.merge(other_spec_set)
+      specs = new_spec_set.to_a.map(&:full_name)
+      expect(specs).to include("a-1.0")
+      expect(specs).to include("f-1.0")
+    end
+  end
+
+  describe "#to_a" do
+    it "returns the specs in order" do
+      expect(subject.to_a.map(&:full_name)).to eq %w[
+        a-1.0
+        b-1.0
+        e-1.0.0.pre.1
+        c-1.1
+        d-2.0
+      ]
+    end
+  end
+end
diff --git a/spec/bundler/bundler/ssl_certs/certificate_manager_spec.rb b/spec/bundler/bundler/ssl_certs/certificate_manager_spec.rb
new file mode 100644
index 0000000000..4250bfc497
--- /dev/null
+++ b/spec/bundler/bundler/ssl_certs/certificate_manager_spec.rb
@@ -0,0 +1,140 @@
+# frozen_string_literal: true
+
+require "bundler/ssl_certs/certificate_manager"
+
+RSpec.describe Bundler::SSLCerts::CertificateManager do
+  let(:rubygems_path)      { root }
+  let(:stub_cert)          { File.join(root.to_s, "lib", "rubygems", "ssl_certs", "rubygems.org", "ssl-cert.pem") }
+  let(:rubygems_certs_dir) { File.join(root.to_s, "lib", "rubygems", "ssl_certs", "rubygems.org") }
+
+  subject { described_class.new(rubygems_path) }
+
+  # Pretend bundler root is rubygems root
+  before do
+    # Backing up rubygems ceriticates
+    FileUtils.mv(rubygems_certs_dir, rubygems_certs_dir + ".back") if ENV["BUNDLE_RUBY"] && ENV["BUNDLE_GEM"]
+
+    FileUtils.mkdir_p(rubygems_certs_dir)
+    FileUtils.touch(stub_cert)
+  end
+
+  after do
+    FileUtils.rm_rf(rubygems_certs_dir)
+
+    # Restore rubygems certificates
+    FileUtils.mv(rubygems_certs_dir + ".back", rubygems_certs_dir) if ENV["BUNDLE_RUBY"] && ENV["BUNDLE_GEM"]
+  end
+
+  describe "#update_from" do
+    let(:cert_manager) { double(:cert_manager) }
+
+    before { allow(described_class).to receive(:new).with(rubygems_path).and_return(cert_manager) }
+
+    it "should update the certs through a new certificate manager" do
+      allow(cert_manager).to receive(:update!)
+      expect(described_class.update_from!(rubygems_path)).to be_nil
+    end
+  end
+
+  describe "#initialize" do
+    it "should set bundler_cert_path as path of the subdir with bundler ssl certs" do
+      expect(subject.bundler_cert_path).to eq(File.join(root, "lib/bundler/ssl_certs"))
+    end
+
+    it "should set bundler_certs as the paths of the bundler ssl certs" do
+      expect(subject.bundler_certs).to include(File.join(root, "lib/bundler/ssl_certs/rubygems.global.ssl.fastly.net/DigiCertHighAssuranceEVRootCA.pem"))
+      expect(subject.bundler_certs).to include(File.join(root, "lib/bundler/ssl_certs/index.rubygems.org/GlobalSignRootCA.pem"))
+    end
+
+    context "when rubygems_path is not nil" do
+      it "should set rubygems_certs" do
+        expect(subject.rubygems_certs).to include(File.join(root, "lib", "rubygems", "ssl_certs", "rubygems.org", "ssl-cert.pem"))
+      end
+    end
+  end
+
+  describe "#up_to_date?" do
+    context "when bundler certs and rubygems certs are the same" do
+      before do
+        bundler_certs = Dir[File.join(root.to_s, "lib", "bundler", "ssl_certs", "**", "*.pem")]
+        FileUtils.rm(stub_cert)
+        FileUtils.cp(bundler_certs, rubygems_certs_dir)
+      end
+
+      it "should return true" do
+        expect(subject).to be_up_to_date
+      end
+    end
+
+    context "when bundler certs and rubygems certs are not the same" do
+      it "should return false" do
+        expect(subject).to_not be_up_to_date
+      end
+    end
+  end
+
+  describe "#update!" do
+    context "when certificate manager is not up to date" do
+      before do
+        allow(subject).to receive(:up_to_date?).and_return(false)
+        allow(bundler_fileutils).to receive(:rm)
+        allow(bundler_fileutils).to receive(:cp)
+      end
+
+      it "should remove the current bundler certs" do
+        expect(bundler_fileutils).to receive(:rm).with(subject.bundler_certs)
+        subject.update!
+      end
+
+      it "should copy the rubygems certs into bundler certs" do
+        expect(bundler_fileutils).to receive(:cp).with(subject.rubygems_certs, subject.bundler_cert_path)
+        subject.update!
+      end
+
+      it "should return nil" do
+        expect(subject.update!).to be_nil
+      end
+    end
+
+    context "when certificate manager is up to date" do
+      before { allow(subject).to receive(:up_to_date?).and_return(true) }
+
+      it "should return nil" do
+        expect(subject.update!).to be_nil
+      end
+    end
+  end
+
+  describe "#connect_to" do
+    let(:host)                 { "http://www.host.com" }
+    let(:http)                 { Net::HTTP.new(host, 443) }
+    let(:cert_store)           { OpenSSL::X509::Store.new }
+    let(:http_header_response) { double(:http_header_response) }
+
+    before do
+      allow(Net::HTTP).to receive(:new).with(host, 443).and_return(http)
+      allow(OpenSSL::X509::Store).to receive(:new).and_return(cert_store)
+      allow(http).to receive(:head).with("/").and_return(http_header_response)
+    end
+
+    it "should use ssl for the http request" do
+      expect(http).to receive(:use_ssl=).with(true)
+      subject.connect_to(host)
+    end
+
+    it "use verify peer mode" do
+      expect(http).to receive(:verify_mode=).with(OpenSSL::SSL::VERIFY_PEER)
+      subject.connect_to(host)
+    end
+
+    it "set its cert store as a OpenSSL::X509::Store populated with bundler certs" do
+      expect(cert_store).to receive(:add_file).at_least(:once)
+      expect(http).to receive(:cert_store=).with(cert_store)
+      subject.connect_to(host)
+    end
+
+    it "return the headers of the request response" do
+      expect(subject.connect_to(host)).to eq(http_header_response)
+    end
+  end
+end
diff --git a/spec/bundler/bundler/stub_specification_spec.rb b/spec/bundler/bundler/stub_specification_spec.rb
new file mode 100644
index 0000000000..5521d83769
--- /dev/null
+++ b/spec/bundler/bundler/stub_specification_spec.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::StubSpecification do
+  let(:gemspec) do
+    Gem::Specification.new do |s|
+      s.name = "gemname"
+      s.version = "1.0.0"
+      s.loaded_from = __FILE__
+    end
+  end
+
+  let(:with_bundler_stub_spec) do
+    described_class.from_stub(gemspec)
+  end
+
+  if Bundler.rubygems.provides?(">= 2.1")
+    describe "#from_stub" do
+      it "returns the same stub if already a Bundler::StubSpecification" do
+        stub = described_class.from_stub(with_bundler_stub_spec)
+        expect(stub).to be(with_bundler_stub_spec)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/ui/shell_spec.rb b/spec/bundler/bundler/ui/shell_spec.rb
new file mode 100644
index 0000000000..951a446aff
--- /dev/null
+++ b/spec/bundler/bundler/ui/shell_spec.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::UI::Shell do
+  subject { described_class.new }
+
+  before { subject.level = "debug" }
+
+  describe "#info" do
+    before { subject.level = "info" }
+    it "prints to stdout" do
+      expect { subject.info("info") }.to output("info\n").to_stdout
+    end
+  end
+
+  describe "#confirm" do
+    before { subject.level = "confirm" }
+    it "prints to stdout" do
+      expect { subject.confirm("confirm") }.to output("confirm\n").to_stdout
+    end
+  end
+
+  describe "#warn" do
+    before { subject.level = "warn" }
+    it "prints to stdout", :bundler => "< 2" do
+      expect { subject.warn("warning") }.to output("warning\n").to_stdout
+    end
+
+    it "prints to stderr", :bundler => "2" do
+      expect { subject.warn("warning") }.to output("warning\n").to_stderr
+    end
+
+    context "when stderr flag is enabled" do
+      before { Bundler.settings.temporary(:error_on_stderr => true) }
+      it "prints to stderr" do
+        expect { subject.warn("warning!") }.to output("warning!\n").to_stderr
+      end
+    end
+  end
+
+  describe "#debug" do
+    it "prints to stdout" do
+      expect { subject.debug("debug") }.to output("debug\n").to_stdout
+    end
+  end
+
+  describe "#error" do
+    before { subject.level = "error" }
+
+    it "prints to stdout", :bundler => "< 2" do
+      expect { subject.error("error!!!") }.to output("error!!!\n").to_stdout
+    end
+
+    it "prints to stderr", :bundler => "2" do
+      expect { subject.error("error!!!") }.to output("error!!!\n").to_stderr
+    end
+
+    context "when stderr flag is enabled" do
+      before { Bundler.settings.temporary(:error_on_stderr => true) }
+      it "prints to stderr" do
+        expect { subject.error("error!!!") }.to output("error!!!\n").to_stderr
+      end
+
+      context "when stderr is closed" do
+        it "doesn't report anything" do
+          output = capture(:stderr, :closed => true) do
+            subject.error("Something went wrong")
+          end
+          expect(output).to_not eq("Something went wrong\n")
+        end
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/ui_spec.rb b/spec/bundler/bundler/ui_spec.rb
new file mode 100644
index 0000000000..6ef8729277
--- /dev/null
+++ b/spec/bundler/bundler/ui_spec.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::UI do
+  describe Bundler::UI::Silent do
+    it "has the same instance methods as Shell", :ruby => ">= 1.9" do
+      shell = Bundler::UI::Shell
+      methods = proc do |cls|
+        cls.instance_methods.map do |i|
+          m = shell.instance_method(i)
+          [i, m.parameters]
+        end.sort_by(&:first)
+      end
+      expect(methods.call(described_class)).to eq(methods.call(shell))
+    end
+
+    it "has the same instance class as Shell", :ruby => ">= 1.9" do
+      shell = Bundler::UI::Shell
+      methods = proc do |cls|
+        cls.methods.map do |i|
+          m = shell.method(i)
+          [i, m.parameters]
+        end.sort_by(&:first)
+      end
+      expect(methods.call(described_class)).to eq(methods.call(shell))
+    end
+  end
+
+  describe Bundler::UI::Shell do
+    let(:options) { {} }
+    subject { described_class.new(options) }
+    describe "debug?" do
+      it "returns a boolean" do
+        subject.level = :debug
+        expect(subject.debug?).to eq(true)
+
+        subject.level = :error
+        expect(subject.debug?).to eq(false)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/uri_credentials_filter_spec.rb b/spec/bundler/bundler/uri_credentials_filter_spec.rb
new file mode 100644
index 0000000000..fe52d16306
--- /dev/null
+++ b/spec/bundler/bundler/uri_credentials_filter_spec.rb
@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+RSpec.describe Bundler::URICredentialsFilter do
+  subject { described_class }
+
+  describe "#credential_filtered_uri" do
+    shared_examples_for "original type of uri is maintained" do
+      it "maintains same type for return value as uri input type" do
+        expect(subject.credential_filtered_uri(uri)).to be_kind_of(uri.class)
+      end
+    end
+
+    shared_examples_for "sensitive credentials in uri are filtered out" do
+      context "authentication using oauth credentials" do
+        context "specified via 'x-oauth-basic'" do
+          let(:credentials) { "oauth_token:x-oauth-basic@" }
+
+          it "returns the uri without the oauth token" do
+            expect(subject.credential_filtered_uri(uri).to_s).to eq(URI("https://x-oauth-basic@github.com/company/private-repo").to_s)
+          end
+
+          it_behaves_like "original type of uri is maintained"
+        end
+
+        context "specified via 'x'" do
+          let(:credentials) { "oauth_token:x@" }
+
+          it "returns the uri without the oauth token" do
+            expect(subject.credential_filtered_uri(uri).to_s).to eq(URI("https://x@github.com/company/private-repo").to_s)
+          end
+
+          it_behaves_like "original type of uri is maintained"
+        end
+      end
+
+      context "authentication using login credentials" do
+        let(:credentials) { "username1:hunter3@" }
+
+        it "returns the uri without the password" do
+          expect(subject.credential_filtered_uri(uri).to_s).to eq(URI("https://username1@github.com/company/private-repo").to_s)
+        end
+
+        it_behaves_like "original type of uri is maintained"
+      end
+
+      context "authentication without credentials" do
+        let(:credentials) { "" }
+
+        it "returns the same uri" do
+          expect(subject.credential_filtered_uri(uri).to_s).to eq(uri.to_s)
+        end
+
+        it_behaves_like "original type of uri is maintained"
+      end
+    end
+
+    context "uri is a uri object" do
+      let(:uri) { URI("https://#{credentials}github.com/company/private-repo") }
+
+      it_behaves_like "sensitive credentials in uri are filtered out"
+    end
+
+    context "uri is a uri string" do
+      let(:uri) { "https://#{credentials}github.com/company/private-repo" }
+
+      it_behaves_like "sensitive credentials in uri are filtered out"
+    end
+
+    context "uri is a non-uri format string (ex. path)" do
+      let(:uri) { "/path/to/repo" }
+
+      it "returns the same uri" do
+        expect(subject.credential_filtered_uri(uri).to_s).to eq(uri.to_s)
+      end
+
+      it_behaves_like "original type of uri is maintained"
+    end
+
+    context "uri is nil" do
+      let(:uri) { nil }
+
+      it "returns nil" do
+        expect(subject.credential_filtered_uri(uri)).to be_nil
+      end
+
+      it_behaves_like "original type of uri is maintained"
+    end
+  end
+
+  describe "#credential_filtered_string" do
+    let(:str_to_filter) { "This is a git message containing a uri #{uri}!" }
+    let(:credentials)   { "" }
+    let(:uri)           { URI("https://#{credentials}github.com/company/private-repo") }
+
+    context "with a uri that contains credentials" do
+      let(:credentials) { "oauth_token:x-oauth-basic@" }
+
+      it "returns the string without the sensitive credentials" do
+        expect(subject.credential_filtered_string(str_to_filter, uri)).to eq(
+          "This is a git message containing a uri https://x-oauth-basic@github.com/company/private-repo!"
+        )
+      end
+    end
+
+    context "that does not contains credentials" do
+      it "returns the same string" do
+        expect(subject.credential_filtered_string(str_to_filter, uri)).to eq(str_to_filter)
+      end
+    end
+
+    context "string to filter is nil" do
+      let(:str_to_filter) { nil }
+
+      it "returns nil" do
+        expect(subject.credential_filtered_string(str_to_filter, uri)).to be_nil
+      end
+    end
+
+    context "uri to filter out is nil" do
+      let(:uri) { nil }
+
+      it "returns the same string" do
+        expect(subject.credential_filtered_string(str_to_filter, uri)).to eq(str_to_filter)
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/vendored_persistent_spec.rb b/spec/bundler/bundler/vendored_persistent_spec.rb
new file mode 100644
index 0000000000..338431c4a6
--- /dev/null
+++ b/spec/bundler/bundler/vendored_persistent_spec.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+require "bundler/vendored_persistent"
+
+RSpec.describe Bundler::PersistentHTTP do
+  describe "#warn_old_tls_version_rubygems_connection" do
+    let(:uri) { "https://index.rubygems.org" }
+    let(:connection) { instance_double(subject.http_class) }
+    let(:tls_version) { "TLSv1.2" }
+    let(:socket) { double("Socket") }
+    let(:socket_io) { double("SocketIO") }
+
+    before do
+      allow(connection).to receive(:use_ssl?).and_return(!tls_version.nil?)
+      allow(socket).to receive(:io).and_return(socket_io)
+      connection.instance_variable_set(:@socket, socket)
+
+      if tls_version
+        allow(socket_io).to receive(:ssl_version).and_return(tls_version)
+      end
+    end
+
+    shared_examples_for "does not warn" do
+      it "does not warn" do
+        allow(Bundler.ui).to receive(:warn).never
+        subject.warn_old_tls_version_rubygems_connection(URI(uri), connection)
+      end
+    end
+
+    shared_examples_for "does warn" do |*expected|
+      it "warns" do
+        expect(Bundler.ui).to receive(:warn).with(*expected)
+        subject.warn_old_tls_version_rubygems_connection(URI(uri), connection)
+      end
+    end
+
+    context "an HTTPS uri with TLSv1.2" do
+      include_examples "does not warn"
+    end
+
+    context "without SSL" do
+      let(:tls_version) { nil }
+
+      include_examples "does not warn"
+    end
+
+    context "without a socket" do
+      let(:socket) { nil }
+
+      include_examples "does not warn"
+    end
+
+    context "with a different TLD" do
+      let(:uri) { "https://foo.bar" }
+      include_examples "does not warn"
+
+      context "and an outdated TLS version" do
+        let(:tls_version) { "TLSv1" }
+        include_examples "does not warn"
+      end
+    end
+
+    context "with a nonsense TLS version" do
+      let(:tls_version) { "BlahBlah2.0Blah" }
+      include_examples "does not warn"
+    end
+
+    context "with an outdated TLS version" do
+      let(:tls_version) { "TLSv1" }
+      include_examples "does warn",
+        "Warning: Your Ruby version is compiled against a copy of OpenSSL that is very old. " \
+        "Starting in January 2018, RubyGems.org will refuse connection requests from these very old versions of OpenSSL. " \
+        "If you will need to continue installing gems after January 2018, please follow this guide to upgrade: http://ruby.to/tls-outdated.",
+        :wrap => true
+    end
+  end
+end
diff --git a/spec/bundler/bundler/version_ranges_spec.rb b/spec/bundler/bundler/version_ranges_spec.rb
new file mode 100644
index 0000000000..ccbb9285d5
--- /dev/null
+++ b/spec/bundler/bundler/version_ranges_spec.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require "bundler/version_ranges"
+
+RSpec.describe Bundler::VersionRanges do
+  describe ".empty?" do
+    shared_examples_for "empty?" do |exp, *req|
+      it "returns #{exp} for #{req}" do
+        r = Gem::Requirement.new(*req)
+        ranges = described_class.for(r)
+        expect(described_class.empty?(*ranges)).to eq(exp), "expected `#{r}` #{exp ? "" : "not "}to be empty"
+      end
+    end
+
+    include_examples "empty?", false
+    include_examples "empty?", false, "!= 1"
+    include_examples "empty?", false, "!= 1", "= 2"
+    include_examples "empty?", false, "!= 1", "> 1"
+    include_examples "empty?", false, "!= 1", ">= 1"
+    include_examples "empty?", false, "= 1", ">= 0.1", "<= 1.1"
+    include_examples "empty?", false, "= 1", ">= 1", "<= 1"
+    include_examples "empty?", false, "= 1", "~> 1"
+    include_examples "empty?", false, ">= 0.z", "= 0"
+    include_examples "empty?", false, ">= 0"
+    include_examples "empty?", false, ">= 1.0.0", "< 2.0.0"
+    include_examples "empty?", false, "~> 1"
+    include_examples "empty?", false, "~> 2.0", "~> 2.1"
+    include_examples "empty?", true, "!= 1", "< 2", "> 2"
+    include_examples "empty?", true, "!= 1", "<= 1", ">= 1"
+    include_examples "empty?", true, "< 2", "> 2"
+    include_examples "empty?", true, "= 1", "!= 1"
+    include_examples "empty?", true, "= 1", "= 2"
+    include_examples "empty?", true, "= 1", "~> 2"
+    include_examples "empty?", true, ">= 0", "<= 0.a"
+    include_examples "empty?", true, "~> 2.0", "~> 3"
+  end
+end
diff --git a/spec/bundler/bundler/worker_spec.rb b/spec/bundler/bundler/worker_spec.rb
new file mode 100644
index 0000000000..2e5642709d
--- /dev/null
+++ b/spec/bundler/bundler/worker_spec.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require "bundler/worker"
+
+RSpec.describe Bundler::Worker do
+  let(:size) { 5 }
+  let(:name) { "Spec Worker" }
+  let(:function) { proc {|object, worker_number| [object, worker_number] } }
+  subject { described_class.new(size, name, function) }
+
+  after { subject.stop }
+
+  describe "#initialize" do
+    context "when Thread.start raises ThreadError" do
+      it "raises when no threads can be created" do
+        allow(Thread).to receive(:start).and_raise(ThreadError, "error creating thread")
+
+        expect { subject.enq "a" }.to raise_error(Bundler::ThreadCreationError, "Failed to create threads for the Spec Worker worker: error creating thread")
+      end
+    end
+  end
+end
diff --git a/spec/bundler/bundler/yaml_serializer_spec.rb b/spec/bundler/bundler/yaml_serializer_spec.rb
new file mode 100644
index 0000000000..1241c74bbf
--- /dev/null
+++ b/spec/bundler/bundler/yaml_serializer_spec.rb
@@ -0,0 +1,194 @@
+# frozen_string_literal: true
+
+require "bundler/yaml_serializer"
+
+RSpec.describe Bundler::YAMLSerializer do
+  subject(:serializer) { Bundler::YAMLSerializer }
+
+  describe "#dump" do
+    it "works for simple hash" do
+      hash = { "Q" => "Where does Thursday come before Wednesday? In the dictionary. :P" }
+
+      expected = strip_whitespace <<-YAML
+          ---
+          Q: "Where does Thursday come before Wednesday? In the dictionary. :P"
+      YAML
+
+      expect(serializer.dump(hash)).to eq(expected)
+    end
+
+    it "handles nested hash" do
+      hash = {
+        "nice-one" => {
+          "read_ahead" => "All generalizations are false, including this one",
+        },
+      }
+
+      expected = strip_whitespace <<-YAML
+          ---
+          nice-one:
+            read_ahead: "All generalizations are false, including this one"
+      YAML
+
+      expect(serializer.dump(hash)).to eq(expected)
+    end
+
+    it "array inside an hash" do
+      hash = {
+        "nested_hash" => {
+          "contains_array" => [
+            "Jack and Jill went up the hill",
+            "To fetch a pail of water.",
+            "Jack fell down and broke his crown,",
+            "And Jill came tumbling after.",
+          ],
+        },
+      }
+
+      expected = strip_whitespace <<-YAML
+        ---
+        nested_hash:
+          contains_array:
+          - "Jack and Jill went up the hill"
+          - "To fetch a pail of water."
+          - "Jack fell down and broke his crown,"
+          - "And Jill came tumbling after."
+      YAML
+
+      expect(serializer.dump(hash)).to eq(expected)
+    end
+  end
+
+  describe "#load" do
+    it "works for simple hash" do
+      yaml = strip_whitespace <<-YAML
+        ---
+        Jon: "Air is free dude!"
+        Jack: "Yes.. until you buy a bag of chips!"
+      YAML
+
+      hash = {
+        "Jon" => "Air is free dude!",
+        "Jack" => "Yes.. until you buy a bag of chips!",
+      }
+
+      expect(serializer.load(yaml)).to eq(hash)
+    end
+
+    it "works for nested hash" do
+      yaml = strip_whitespace <<-YAML
+        ---
+        baa:
+          baa: "black sheep"
+          have: "you any wool?"
+          yes: "merry have I"
+        three: "bags full"
+      YAML
+
+      hash = {
+        "baa" => {
+          "baa" => "black sheep",
+          "have" => "you any wool?",
+          "yes" => "merry have I",
+        },
+        "three" => "bags full",
+      }
+
+      expect(serializer.load(yaml)).to eq(hash)
+    end
+
+    it "handles colon in key/value" do
+      yaml = strip_whitespace <<-YAML
+        BUNDLE_MIRROR__HTTPS://RUBYGEMS__ORG/: http://rubygems-mirror.org
+      YAML
+
+      expect(serializer.load(yaml)).to eq("BUNDLE_MIRROR__HTTPS://RUBYGEMS__ORG/" => "http://rubygems-mirror.org")
+    end
+
+    it "handles arrays inside hashes" do
+      yaml = strip_whitespace <<-YAML
+        ---
+        nested_hash:
+          contains_array:
+          - "Why shouldn't you write with a broken pencil?"
+          - "Because it's pointless!"
+      YAML
+
+      hash = {
+        "nested_hash" => {
+          "contains_array" => [
+            "Why shouldn't you write with a broken pencil?",
+            "Because it's pointless!",
+          ],
+        },
+      }
+
+      expect(serializer.load(yaml)).to eq(hash)
+    end
+
+    it "handles windows-style CRLF line endings" do
+      yaml = strip_whitespace(<<-YAML).gsub("\n", "\r\n")
+        ---
+        nested_hash:
+          contains_array:
+          - "Why shouldn't you write with a broken pencil?"
+          - "Because it's pointless!"
+          - oh so silly
+      YAML
+
+      hash = {
+        "nested_hash" => {
+          "contains_array" => [
+            "Why shouldn't you write with a broken pencil?",
+            "Because it's pointless!",
+            "oh so silly",
+          ],
+        },
+      }
+
+      expect(serializer.load(yaml)).to eq(hash)
+    end
+  end
+
+  describe "against yaml lib" do
+    let(:hash) do
+      {
+        "a_joke" => {
+          "my-stand" => "I can totally keep secrets",
+          "but" => "The people I tell them to can't :P",
+          "wouldn't it be funny if this string were empty?" => "",
+        },
+        "more" => {
+          "first" => [
+            "Can a kangaroo jump higher than a house?",
+            "Of course, a house doesn't jump at all.",
+          ],
+          "second" => [
+            "What did the sea say to the sand?",
+            "Nothing, it simply waved.",
+          ],
+          "array with empty string" => [""],
+        },
+        "sales" => {
+          "item" => "A Parachute",
+          "description" => "Only used once, never opened.",
+        },
+        "one-more" => "I'd tell you a chemistry joke but I know I wouldn't get a reaction.",
+      }
+    end
+
+    context "#load" do
+      it "retrieves the original hash" do
+        require "yaml"
+        expect(serializer.load(YAML.dump(hash))).to eq(hash)
+      end
+    end
+
+    context "#dump" do
+      it "retrieves the original hash" do
+        require "yaml"
+        expect(YAML.load(serializer.dump(hash))).to eq(hash)
+      end
+    end
+  end
+end