Sync rubygems with current master (#2889)

33 files changed, 433 insertions, 558 deletions

diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index f7380c7154..9bd4e9be20 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -190,6 +190,8 @@ module Gem
   @pre_reset_hooks      ||= []
   @post_reset_hooks     ||= []
 
+  @default_source_date_epoch = nil
+
   ##
   # Try to activate a gem containing +path+. Returns true if
   # activation succeeded or wasn't needed because it was already
@@ -317,6 +319,13 @@ module Gem
   end
 
   ##
+  # The path were rubygems plugins are to be installed.
+
+  def self.plugindir(install_dir=Gem.dir)
+    File.join install_dir, 'plugins'
+  end
+
+  ##
   # Reset the +dir+ and +path+ values.  The next time +dir+ or +path+
   # is requested, the values will be calculated from scratch.  This is
   # mainly used by the unit tests to provide test isolation.
@@ -423,10 +432,6 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     paths.spec_cache_dir
   end
 
-  def self.plugins_dir
-    File.join(dir, "plugins")
-  end
-
   ##
   # Quietly ensure the Gem directory +dir+ contains all the proper
   # subdirectories.  If we can't create a directory due to a permission
@@ -466,7 +471,10 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     subdirs.each do |name|
       subdir = File.join dir, name
       next if File.exist? subdir
-      FileUtils.mkdir_p subdir, **options rescue nil
+      begin
+        FileUtils.mkdir_p subdir, **options
+      rescue Errno::EACCES
+      end
     end
   ensure
     File.umask old_umask
@@ -863,8 +871,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
 
   def self.ruby
     if @ruby.nil?
-      @ruby = File.join(RbConfig::CONFIG['bindir'],
-                        "#{RbConfig::CONFIG['ruby_install_name']}#{RbConfig::CONFIG['EXEEXT']}")
+      @ruby = RbConfig.ruby
 
       @ruby = "\"#{@ruby}\"" if @ruby =~ /\s/
     end
@@ -1099,7 +1106,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   # Find rubygems plugin files in the standard location and load them
 
   def self.load_plugins
-    load_plugin_files Gem::Util.glob_files_in_dir("*#{Gem.plugin_suffix_pattern}", plugins_dir)
+    load_plugin_files Gem::Util.glob_files_in_dir("*#{Gem.plugin_suffix_pattern}", plugindir)
   end
 
   ##
@@ -1182,20 +1189,43 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   end
 
   ##
-  # The SOURCE_DATE_EPOCH environment variable (or, if that's not set, the current time), converted to Time object.
-  # This is used throughout RubyGems for enabling reproducible builds.
+  # If the SOURCE_DATE_EPOCH environment variable is set, returns it's value.
+  # Otherwise, returns the time that `Gem.source_date_epoch_string` was
+  # first called in the same format as SOURCE_DATE_EPOCH.
+  #
+  # NOTE(@duckinator): The implementation is a tad weird because we want to:
+  #   1. Make builds reproducible by default, by having this function always
+  #      return the same result during a given run.
+  #   2. Allow changing ENV['SOURCE_DATE_EPOCH'] at runtime, since multiple
+  #      tests that set this variable will be run in a single process.
   #
-  # If it is not set as an environment variable already, this also sets it.
+  # If you simplify this function and a lot of tests fail, that is likely
+  # due to #2 above.
   #
   # Details on SOURCE_DATE_EPOCH:
   # https://reproducible-builds.org/specs/source-date-epoch/
 
-  def self.source_date_epoch
-    if ENV["SOURCE_DATE_EPOCH"].nil? || ENV["SOURCE_DATE_EPOCH"].empty?
-      ENV["SOURCE_DATE_EPOCH"] = Time.now.to_i.to_s
-    end
+  def self.source_date_epoch_string
+    # The value used if $SOURCE_DATE_EPOCH is not set.
+    @default_source_date_epoch ||= Time.now.to_i.to_s
+
+    specified_epoch = ENV["SOURCE_DATE_EPOCH"]
+
+    # If it's empty or just whitespace, treat it like it wasn't set at all.
+    specified_epoch = nil if !specified_epoch.nil? && specified_epoch.strip.empty?
+
+    epoch = specified_epoch || @default_source_date_epoch
+
+    epoch.strip
+  end
 
-    Time.at(ENV["SOURCE_DATE_EPOCH"].to_i).utc.freeze
+  ##
+  # Returns the value of Gem.source_date_epoch_string, as a Time object.
+  #
+  # This is used throughout RubyGems for enabling reproducible builds.
+
+  def self.source_date_epoch
+    Time.at(self.source_date_epoch_string.to_i).utc.freeze
   end
 
   # FIX: Almost everywhere else we use the `def self.` way of defining class
diff --git a/lib/rubygems/bundler_version_finder.rb b/lib/rubygems/bundler_version_finder.rb
index 38da7738a8..ea6698f26e 100644
--- a/lib/rubygems/bundler_version_finder.rb
+++ b/lib/rubygems/bundler_version_finder.rb
@@ -82,12 +82,19 @@ To install the missing version, run `gem install bundler:#{vr.first}`
   def self.lockfile_contents
     gemfile = ENV["BUNDLE_GEMFILE"]
     gemfile = nil if gemfile && gemfile.empty?
-    Gem::Util.traverse_parents Dir.pwd do |directory|
-      next unless gemfile = Gem::GEM_DEP_FILES.find { |f| File.file?(f.tap(&Gem::UNTAINT)) }
 
-      gemfile = File.join directory, gemfile
-      break
-    end unless gemfile
+    unless gemfile
+      begin
+        Gem::Util.traverse_parents(Dir.pwd) do |directory|
+          next unless gemfile = Gem::GEM_DEP_FILES.find { |f| File.file?(f.tap(&Gem::UNTAINT)) }
+
+          gemfile = File.join directory, gemfile
+          break
+        end
+      rescue Errno::ENOENT
+        return
+      end
+    end
 
     return unless gemfile
 
diff --git a/lib/rubygems/command.rb b/lib/rubygems/command.rb
index 11b6645e9d..9b7b41d3a7 100644
--- a/lib/rubygems/command.rb
+++ b/lib/rubygems/command.rb
@@ -77,7 +77,7 @@ class Gem::Command
     when Array
       @extra_args = value
     when String
-      @extra_args = value.split(' ')
+      @extra_args = value.split
     end
   end
 
@@ -174,8 +174,7 @@ class Gem::Command
     alert_error msg
 
     unless suppress_suggestions
-      suggestions = Gem::SpecFetcher.fetcher.suggest_gems_from_name gem_name
-
+      suggestions = Gem::SpecFetcher.fetcher.suggest_gems_from_name(gem_name, :latest, 10)
       unless suggestions.empty?
         alert_error "Possible alternatives: #{suggestions.join(", ")}"
       end
@@ -625,8 +624,7 @@ class Gem::Command
   # :stopdoc:
 
   HELP = <<-HELP.freeze
-RubyGems is a sophisticated package manager for Ruby.  This is a
-basic help message containing pointers to more information.
+RubyGems is a package manager for Ruby.
 
   Usage:
     gem -h/--help
diff --git a/lib/rubygems/commands/contents_command.rb b/lib/rubygems/commands/contents_command.rb
index 26d6828fe6..989ca5855c 100644
--- a/lib/rubygems/commands/contents_command.rb
+++ b/lib/rubygems/commands/contents_command.rb
@@ -167,7 +167,7 @@ prefix or only the files that are requireable.
   end
 
   def spec_for(name)
-    spec = Gem::Specification.find_all_by_name(name, @version).last
+    spec = Gem::Specification.find_all_by_name(name, @version).first
 
     return spec if spec
 
diff --git a/lib/rubygems/commands/update_command.rb b/lib/rubygems/commands/update_command.rb
index 7031ac0dd0..494b3eef67 100644
--- a/lib/rubygems/commands/update_command.rb
+++ b/lib/rubygems/commands/update_command.rb
@@ -184,14 +184,14 @@ command to remove old versions.
     else
       require "tmpdir"
       tmpdir = Dir.mktmpdir
-      FileUtils.mv Gem.plugins_dir, tmpdir
+      FileUtils.mv Gem.plugindir, tmpdir
 
       status = yield
 
       if status
         FileUtils.rm_rf tmpdir
       else
-        FileUtils.mv File.join(tmpdir, "plugins"), Gem.plugins_dir
+        FileUtils.mv File.join(tmpdir, "plugins"), Gem.plugindir
       end
 
       status
diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index 60f4d18712..a8d170f13a 100644
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -43,18 +43,21 @@ module Kernel
     # https://github.com/rubygems/rubygems/pull/1868
     resolved_path = begin
       rp = nil
-      $LOAD_PATH[0...Gem.load_path_insert_index || -1].each do |lp|
-        safe_lp = lp.dup.tap(&Gem::UNTAINT)
-        begin
-          if File.symlink? safe_lp # for backward compatibility
-            next
+      Gem.suffixes.each do |s|
+        load_path_insert_index = Gem.load_path_insert_index
+        break unless load_path_insert_index
+
+        $LOAD_PATH[0...load_path_insert_index].each do |lp|
+          safe_lp = lp.dup.tap(&Gem::UNTAINT)
+          begin
+            if File.symlink? safe_lp # for backward compatibility
+              next
+            end
+          rescue SecurityError
+            RUBYGEMS_ACTIVATION_MONITOR.exit
+            raise
           end
-        rescue SecurityError
-          RUBYGEMS_ACTIVATION_MONITOR.exit
-          raise
-        end
 
-        Gem.suffixes.each do |s|
           full_path = File.expand_path(File.join(safe_lp, "#{path}#{s}"))
           if File.file?(full_path)
             rp = full_path
@@ -67,12 +70,8 @@ module Kernel
     end
 
     if resolved_path
-      begin
-        RUBYGEMS_ACTIVATION_MONITOR.exit
-        return gem_original_require(resolved_path)
-      rescue LoadError
-        RUBYGEMS_ACTIVATION_MONITOR.enter
-      end
+      RUBYGEMS_ACTIVATION_MONITOR.exit
+      return gem_original_require(resolved_path)
     end
 
     if spec = Gem.find_unresolved_default_spec(path)
diff --git a/lib/rubygems/dependency_installer.rb b/lib/rubygems/dependency_installer.rb
index 6d45688888..14ff8beab2 100644
--- a/lib/rubygems/dependency_installer.rb
+++ b/lib/rubygems/dependency_installer.rb
@@ -7,7 +7,6 @@ require 'rubygems/spec_fetcher'
 require 'rubygems/user_interaction'
 require 'rubygems/source'
 require 'rubygems/available_set'
-require 'rubygems/deprecate'
 
 ##
 # Installs a gem along with all its dependencies from local and remote gems.
@@ -15,7 +14,6 @@ require 'rubygems/deprecate'
 class Gem::DependencyInstaller
 
   include Gem::UserInteraction
-  extend Gem::Deprecate
 
   DEFAULT_OPTIONS = { # :nodoc:
     :env_shebang         => false,
@@ -107,27 +105,6 @@ class Gem::DependencyInstaller
   end
 
   ##
-  # Creates an AvailableSet to install from based on +dep_or_name+ and
-  # +version+
-
-  def available_set_for(dep_or_name, version) # :nodoc:
-    if String === dep_or_name
-      Gem::Deprecate.skip_during do
-        find_spec_by_name_and_version dep_or_name, version, @prerelease
-      end
-    else
-      dep = dep_or_name.dup
-      dep.prerelease = @prerelease
-      @available = Gem::Deprecate.skip_during do
-        find_gems_with_sources dep
-      end
-    end
-
-    @available.pick_best!
-  end
-  deprecate :available_set_for, :none, 2019, 12
-
-  ##
   # Indicated, based on the requested domain, if local
   # gems should be considered.
 
@@ -143,131 +120,6 @@ class Gem::DependencyInstaller
     @domain == :both or @domain == :remote
   end
 
-  ##
-  # Returns a list of pairs of gemspecs and source_uris that match
-  # Gem::Dependency +dep+ from both local (Dir.pwd) and remote (Gem.sources)
-  # sources.  Gems are sorted with newer gems preferred over older gems, and
-  # local gems preferred over remote gems.
-
-  def find_gems_with_sources(dep, best_only=false) # :nodoc:
-    set = Gem::AvailableSet.new
-
-    if consider_local?
-      sl = Gem::Source::Local.new
-
-      if spec = sl.find_gem(dep.name)
-        if dep.matches_spec? spec
-          set.add spec, sl
-        end
-      end
-    end
-
-    if consider_remote?
-      begin
-        # This is pulled from #spec_for_dependency to allow
-        # us to filter tuples before fetching specs.
-        tuples, errors = Gem::SpecFetcher.fetcher.search_for_dependency dep
-
-        if best_only && !tuples.empty?
-          tuples.sort! do |a,b|
-            if b[0].version == a[0].version
-              if b[0].platform != Gem::Platform::RUBY
-                1
-              else
-                -1
-              end
-            else
-              b[0].version <=> a[0].version
-            end
-          end
-          tuples = [tuples.first]
-        end
-
-        specs = []
-        tuples.each do |tup, source|
-          begin
-            spec = source.fetch_spec(tup)
-          rescue Gem::RemoteFetcher::FetchError => e
-            errors << Gem::SourceFetchProblem.new(source, e)
-          else
-            specs << [spec, source]
-          end
-        end
-
-        if @errors
-          @errors += errors
-        else
-          @errors = errors
-        end
-
-        set << specs
-
-      rescue Gem::RemoteFetcher::FetchError => e
-        # FIX if there is a problem talking to the network, we either need to always tell
-        # the user (no really_verbose) or fail hard, not silently tell them that we just
-        # couldn't find their requested gem.
-        verbose do
-          "Error fetching remote data:\t\t#{e.message}\n" \
-            "Falling back to local-only install"
-        end
-        @domain = :local
-      end
-    end
-
-    set
-  end
-  deprecate :find_gems_with_sources, :none, 2019, 12
-
-  ##
-  # Finds a spec and the source_uri it came from for gem +gem_name+ and
-  # +version+.  Returns an Array of specs and sources required for
-  # installation of the gem.
-
-  def find_spec_by_name_and_version(gem_name,
-                                    version = Gem::Requirement.default,
-                                    prerelease = false)
-    set = Gem::AvailableSet.new
-
-    if consider_local?
-      if gem_name =~ /\.gem$/ and File.file? gem_name
-        src = Gem::Source::SpecificFile.new(gem_name)
-        set.add src.spec, src
-      elsif gem_name =~ /\.gem$/
-        Dir[gem_name].each do |name|
-          begin
-            src = Gem::Source::SpecificFile.new name
-            set.add src.spec, src
-          rescue Gem::Package::FormatError
-          end
-        end
-      else
-        local = Gem::Source::Local.new
-
-        if s = local.find_gem(gem_name, version)
-          set.add s, local
-        end
-      end
-    end
-
-    if set.empty?
-      dep = Gem::Dependency.new gem_name, version
-      dep.prerelease = true if prerelease
-
-      set = Gem::Deprecate.skip_during do
-        find_gems_with_sources(dep, true)
-      end
-
-      set.match_platform!
-    end
-
-    if set.empty?
-      raise Gem::SpecificGemNotFoundException.new(gem_name, version, @errors)
-    end
-
-    @available = set
-  end
-  deprecate :find_spec_by_name_and_version, :none, 2019, 12
-
   def in_background(what) # :nodoc:
     fork_happened = false
     if @build_docs_in_background and Process.respond_to?(:fork)
diff --git a/lib/rubygems/ext/builder.rb b/lib/rubygems/ext/builder.rb
index 2fc1074d92..a8bd4c8d1b 100644
--- a/lib/rubygems/ext/builder.rb
+++ b/lib/rubygems/ext/builder.rb
@@ -68,7 +68,9 @@ class Gem::Ext::Builder
       results << (command.respond_to?(:shelljoin) ? command.shelljoin : command)
 
       require "open3"
-      output, status = Open3.capture2e(*command)
+      # Set $SOURCE_DATE_EPOCH for the subprocess.
+      env = {'SOURCE_DATE_EPOCH' => Gem.source_date_epoch_string}
+      output, status = Open3.capture2e(env, *command)
       if verbose
         puts output
       else
diff --git a/lib/rubygems/install_update_options.rb b/lib/rubygems/install_update_options.rb
index 38a0682958..dbf787c7ba 100644
--- a/lib/rubygems/install_update_options.rb
+++ b/lib/rubygems/install_update_options.rb
@@ -25,8 +25,8 @@ module Gem::InstallUpdateOptions
     end
 
     add_option(:"Install/Update", '-n', '--bindir DIR',
-               'Directory where executables are',
-               'located') do |value, options|
+               'Directory where executables will be',
+               'placed when the gem is installed') do |value, options|
       options[:bin_dir] = File.expand_path(value)
     end
 
diff --git a/lib/rubygems/installer.rb b/lib/rubygems/installer.rb
index 2ba92482cc..abb7048b00 100644
--- a/lib/rubygems/installer.rb
+++ b/lib/rubygems/installer.rb
@@ -47,11 +47,6 @@ class Gem::Installer
   include Gem::InstallerUninstallerUtils
 
   ##
-  # Filename of the gem being installed.
-
-  attr_reader :gem
-
-  ##
   # The directory a gem's executables will be installed into
 
   attr_reader :bin_dir
@@ -487,13 +482,7 @@ class Gem::Installer
   def generate_bin # :nodoc:
     return if spec.executables.nil? or spec.executables.empty?
 
-    begin
-      Dir.mkdir @bin_dir, *[options[:dir_mode] && 0755].compact
-    rescue SystemCallError
-      raise unless File.directory? @bin_dir
-    end
-
-    raise Gem::FilePermissionError.new(@bin_dir) unless File.writable? @bin_dir
+    ensure_writable_dir @bin_dir
 
     spec.executables.each do |filename|
       filename.tap(&Gem::UNTAINT)
@@ -523,10 +512,12 @@ class Gem::Installer
     latest = Gem::Specification.latest_spec_for(spec.name)
     return if latest && latest.version > spec.version
 
+    ensure_writable_dir @plugins_dir
+
     if spec.plugins.empty?
-      remove_plugins_for(spec)
+      remove_plugins_for(spec, @plugins_dir)
     else
-      regenerate_plugins_for(spec)
+      regenerate_plugins_for(spec, @plugins_dir)
     end
   end
 
@@ -690,6 +681,7 @@ class Gem::Installer
     @force               = options[:force]
     @install_dir         = options[:install_dir]
     @gem_home            = options[:install_dir] || Gem.dir
+    @plugins_dir         = Gem.plugindir(@gem_home)
     @ignore_dependencies = options[:ignore_dependencies]
     @format_executable   = options[:format_executable]
     @wrappers            = options[:wrappers]
@@ -890,6 +882,13 @@ TEXT
   end
 
   ##
+  # Filename of the gem being installed.
+
+  def gem
+    @package.gem.path
+  end
+
+  ##
   # Performs various checks before installing the gem such as the install
   # repository is writable and its directories exist, required Ruby and
   # rubygems versions are met and that dependencies are installed.
@@ -953,4 +952,14 @@ TEXT
     @package.copy_to cache_file
   end
 
+  def ensure_writable_dir(dir) # :nodoc:
+    begin
+      Dir.mkdir dir, *[options[:dir_mode] && 0755].compact
+    rescue SystemCallError
+      raise unless File.directory? dir
+    end
+
+    raise Gem::FilePermissionError.new(dir) unless File.writable? dir
+  end
+
 end
diff --git a/lib/rubygems/installer_uninstaller_utils.rb b/lib/rubygems/installer_uninstaller_utils.rb
index b8436f4f0a..e81ed4cba3 100644
--- a/lib/rubygems/installer_uninstaller_utils.rb
+++ b/lib/rubygems/installer_uninstaller_utils.rb
@@ -5,9 +5,9 @@
 
 module Gem::InstallerUninstallerUtils
 
-  def regenerate_plugins_for(spec)
+  def regenerate_plugins_for(spec, plugins_dir)
     spec.plugins.each do |plugin|
-      plugin_script_path = File.join Gem.plugins_dir, "#{spec.name}_plugin#{File.extname(plugin)}"
+      plugin_script_path = File.join plugins_dir, "#{spec.name}_plugin#{File.extname(plugin)}"
 
       File.open plugin_script_path, 'wb' do |file|
         file.puts "require '#{plugin}'"
@@ -17,8 +17,8 @@ module Gem::InstallerUninstallerUtils
     end
   end
 
-  def remove_plugins_for(spec)
-    FileUtils.rm_f Gem::Util.glob_files_in_dir("#{spec.name}#{Gem.plugin_suffix_pattern}", Gem.plugins_dir)
+  def remove_plugins_for(spec, plugins_dir)
+    FileUtils.rm_f Gem::Util.glob_files_in_dir("#{spec.name}#{Gem.plugin_suffix_pattern}", plugins_dir)
   end
 
 end
diff --git a/lib/rubygems/source_specific_file.rb b/lib/rubygems/source_specific_file.rb
deleted file mode 100644
index b676b1d3a2..0000000000
--- a/lib/rubygems/source_specific_file.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-# frozen_string_literal: true
-require 'rubygems/source/specific_file'
-
-unless Gem::Deprecate.skip
-  Kernel.warn "#{Gem.location_of_caller(3).join(':')}: Warning: Requiring rubygems/source_specific_file is deprecated; please use rubygems/source/specific_file instead."
-end
diff --git a/lib/rubygems/spec_fetcher.rb b/lib/rubygems/spec_fetcher.rb
index cf86b72188..56ccaea84d 100644
--- a/lib/rubygems/spec_fetcher.rb
+++ b/lib/rubygems/spec_fetcher.rb
@@ -171,30 +171,33 @@ class Gem::SpecFetcher
   # Suggests gems based on the supplied +gem_name+. Returns an array of
   # alternative gem names.
 
-  def suggest_gems_from_name(gem_name, type = :latest)
+  def suggest_gems_from_name(gem_name, type = :latest, num_results = 5)
     gem_name        = gem_name.downcase.tr('_-', '')
     max             = gem_name.size / 2
     names           = available_specs(type).first.values.flatten(1)
 
     matches = names.map do |n|
       next unless n.match_platform?
-
-      distance = levenshtein_distance gem_name, n.name.downcase.tr('_-', '')
-
-      next if distance >= max
-
-      return [n.name] if distance == 0
-
-      [n.name, distance]
+      [n.name, 0] if n.name.downcase.tr('_-', '').include?(gem_name)
     end.compact
 
+    if matches.length < num_results
+      matches += names.map do |n|
+        next unless n.match_platform?
+        distance = levenshtein_distance gem_name, n.name.downcase.tr('_-', '')
+        next if distance >= max
+        return [n.name] if distance == 0
+        [n.name, distance]
+      end.compact
+    end
+
     matches = if matches.empty? && type != :prerelease
                 suggest_gems_from_name gem_name, :prerelease
               else
                 matches.uniq.sort_by { |name, dist| dist }
               end
 
-    matches.first(5).map { |name, dist| name }
+    matches.map { |name, dist| name }.uniq.first(num_results)
   end
 
   ##
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index ad43a63e80..3181303c30 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -790,16 +790,6 @@ class Gem::Specification < Gem::BasicSpecification
   end
   private_class_method :map_stubs
 
-  def self.uniq_by(list, &block) # :nodoc:
-    list.uniq(&block)
-  end
-  private_class_method :uniq_by
-
-  def self.sort_by!(list, &block)
-    list.sort_by!(&block)
-  end
-  private_class_method :sort_by!
-
   def self.each_spec(dirs) # :nodoc:
     each_gemspec(dirs) do |path|
       spec = self.load path
@@ -814,7 +804,7 @@ class Gem::Specification < Gem::BasicSpecification
     @@stubs ||= begin
       pattern = "*.gemspec"
       stubs = Gem.loaded_specs.values + installed_stubs(dirs, pattern) + default_stubs(pattern)
-      stubs = uniq_by(stubs) { |stub| stub.full_name }
+      stubs = stubs.uniq { |stub| stub.full_name }
 
       _resort!(stubs)
       @@stubs_by_name = stubs.select { |s| Gem::Platform.match s.platform }.group_by(&:name)
@@ -847,7 +837,7 @@ class Gem::Specification < Gem::BasicSpecification
       stubs = Gem.loaded_specs.values +
         installed_stubs(dirs, pattern).select { |s| Gem::Platform.match s.platform } +
         default_stubs(pattern)
-      stubs = uniq_by(stubs) { |stub| stub.full_name }.group_by(&:name)
+      stubs = stubs.uniq { |stub| stub.full_name }.group_by(&:name)
       stubs.each_value { |v| _resort!(v) }
 
       @@stubs_by_name.merge! stubs
diff --git a/lib/rubygems/test_case.rb b/lib/rubygems/test_case.rb
index 691985dcd2..ebfe979a1b 100644
--- a/lib/rubygems/test_case.rb
+++ b/lib/rubygems/test_case.rb
@@ -78,6 +78,20 @@ module Gem
   end
 end
 
+require "rubygems/command"
+
+class Gem::Command
+
+  ##
+  # Allows resetting the hash of specific args per command.  This method is
+  # available when requiring 'rubygems/test_case'
+
+  def self.specific_extra_args_hash=(value)
+    @specific_extra_args_hash = value
+  end
+
+end
+
 ##
 # RubyGemTestCase provides a variety of methods for testing rubygems and
 # gem-related behavior in a sandbox.  Through RubyGemTestCase you can install
@@ -1246,10 +1260,7 @@ Also, a list:
     end
 
     begin
-      require "rbconfig"
-      File.join(RbConfig::CONFIG["bindir"],
-                RbConfig::CONFIG["ruby_install_name"] +
-                RbConfig::CONFIG["EXEEXT"])
+      Gem.ruby
     rescue LoadError
       "ruby"
     end
diff --git a/lib/rubygems/uninstaller.rb b/lib/rubygems/uninstaller.rb
index 1766423429..69893dfb76 100644
--- a/lib/rubygems/uninstaller.rb
+++ b/lib/rubygems/uninstaller.rb
@@ -50,6 +50,7 @@ class Gem::Uninstaller
     @gem                = gem
     @version            = options[:version] || Gem::Requirement.default
     @gem_home           = File.realpath(options[:install_dir] || Gem.dir)
+    @plugins_dir        = Gem.plugindir(@gem_home)
     @force_executables  = options[:executables]
     @force_all          = options[:all]
     @force_ignore       = options[:ignore]
@@ -281,7 +282,7 @@ class Gem::Uninstaller
   def remove_plugins(spec) # :nodoc:
     return if spec.plugins.empty?
 
-    remove_plugins_for(spec)
+    remove_plugins_for(spec, @plugins_dir)
   end
 
   ##
@@ -291,7 +292,7 @@ class Gem::Uninstaller
     latest = Gem::Specification.latest_spec_for(@spec.name)
     return if latest.nil?
 
-    regenerate_plugins_for(latest)
+    regenerate_plugins_for(latest, @plugins_dir)
   end
 
   ##
diff --git a/test/rubygems/test_gem.rb b/test/rubygems/test_gem.rb
index 2890e13dfb..fd9b3609f2 100644
--- a/test/rubygems/test_gem.rb
+++ b/test/rubygems/test_gem.rb
@@ -1016,16 +1016,16 @@ class TestGem < Gem::TestCase
   end
 
   def test_self_ruby_escaping_spaces_in_path
-    with_bindir_and_exeext("C:/Ruby 1.8/bin", ".exe") do
-      ruby_install_name "ruby" do
+    with_clean_path_to_ruby do
+      with_rb_config_ruby("C:/Ruby 1.8/bin/ruby.exe") do
         assert_equal "\"C:/Ruby 1.8/bin/ruby.exe\"", Gem.ruby
       end
     end
   end
 
   def test_self_ruby_path_without_spaces
-    with_bindir_and_exeext("C:/Ruby18/bin", ".exe") do
-      ruby_install_name "ruby" do
+    with_clean_path_to_ruby do
+      with_rb_config_ruby("C:/Ruby18/bin/ruby.exe") do
         assert_equal "C:/Ruby18/bin/ruby.exe", Gem.ruby
       end
     end
@@ -1906,6 +1906,24 @@ You may need to `gem install -g` to install missing gems
     assert platform_defaults.is_a? Hash
   end
 
+  # Ensure that `Gem.source_date_epoch` is consistent even if
+  # $SOURCE_DATE_EPOCH has not been set.
+  def test_default_source_date_epoch_doesnt_change
+    old_epoch = ENV['SOURCE_DATE_EPOCH']
+    ENV['SOURCE_DATE_EPOCH'] = nil
+
+    # Unfortunately, there is no real way to test this aside from waiting
+    # enough for `Time.now.to_i` to change -- which is a whole second.
+    #
+    # Fortunately, we only need to do this once.
+    a = Gem.source_date_epoch
+    sleep 1
+    b = Gem.source_date_epoch
+    assert_equal a, b
+  ensure
+    ENV['SOURCE_DATE_EPOCH'] = old_epoch
+  end
+
   def ruby_install_name(name)
     with_clean_path_to_ruby do
       orig_RUBY_INSTALL_NAME = RbConfig::CONFIG['ruby_install_name']
@@ -1923,11 +1941,24 @@ You may need to `gem install -g` to install missing gems
     end
   end
 
-  def with_bindir_and_exeext(bindir, exeext)
-    bindir(bindir) do
-      exeext(exeext) do
-        yield
-      end
+  def with_rb_config_ruby(path)
+    rb_config_singleton_class = class << RbConfig; self; end
+    orig_path = RbConfig.ruby
+
+    redefine_method(rb_config_singleton_class, :ruby, path)
+
+    yield
+  ensure
+    redefine_method(rb_config_singleton_class, :ruby, orig_path)
+  end
+
+  def redefine_method(base, method, new_result)
+    if RUBY_VERSION >= "2.5"
+      base.alias_method(method, method)
+      base.define_method(method) { new_result }
+    else
+      base.send(:alias_method, method, method)
+      base.send(:define_method, method) { new_result }
     end
   end
 
diff --git a/test/rubygems/test_gem_bundler_version_finder.rb b/test/rubygems/test_gem_bundler_version_finder.rb
index 34a451b64d..16ff2956f0 100644
--- a/test/rubygems/test_gem_bundler_version_finder.rb
+++ b/test/rubygems/test_gem_bundler_version_finder.rb
@@ -78,6 +78,23 @@ class TestGemBundlerVersionFinder < Gem::TestCase
     end
   end
 
+  def test_deleted_directory
+    skip "Cannot perform this test on windows" if win_platform?
+    require "tmpdir"
+
+    orig_dir = Dir.pwd
+
+    begin
+      Dir.mktmpdir("some_dir") do |dir|
+        Dir.chdir(dir)
+      end
+    ensure
+      Dir.chdir(orig_dir)
+    end
+
+    assert_nil bvf.bundler_version_with_reason
+  end
+
   def test_compatible
     assert bvf.compatible?(util_spec("foo"))
     assert bvf.compatible?(util_spec("bundler", 1.1))
diff --git a/test/rubygems/test_gem_commands_contents_command.rb b/test/rubygems/test_gem_commands_contents_command.rb
index a8d6efe794..93ebcca5bb 100644
--- a/test/rubygems/test_gem_commands_contents_command.rb
+++ b/test/rubygems/test_gem_commands_contents_command.rb
@@ -105,6 +105,22 @@ class TestGemCommandsContentsCommand < Gem::TestCase
     assert_empty @ui.error
   end
 
+  def test_execute_missing_version
+    @cmd.options[:args] = %w[foo]
+    @cmd.options[:version] = Gem::Requirement.new '= 2'
+
+    gem 'foo', 1
+
+    assert_raises Gem::MockGemUi::TermError do
+      use_ui @ui do
+        @cmd.execute
+      end
+    end
+
+    assert_match "Unable to find gem 'foo'", @ui.output
+    assert_empty @ui.error
+  end
+
   def test_execute_missing_multiple
     @cmd.options[:args] = %w[foo bar]
 
@@ -152,6 +168,23 @@ class TestGemCommandsContentsCommand < Gem::TestCase
     assert_equal "", @ui.error
   end
 
+  def test_execute_show_install_dir_latest_version
+    @cmd.options[:args] = %w[foo]
+    @cmd.options[:show_install_dir] = true
+
+    gem 'foo', 1
+    gem 'foo', 2
+
+    use_ui @ui do
+      @cmd.execute
+    end
+
+    expected = File.join @gemhome, 'gems', 'foo-2'
+
+    assert_equal "#{expected}\n", @ui.output
+    assert_equal "", @ui.error
+  end
+
   def test_execute_show_install_dir_version
     @cmd.options[:args] = %w[foo]
     @cmd.options[:show_install_dir] = true
diff --git a/test/rubygems/test_gem_commands_pristine_command.rb b/test/rubygems/test_gem_commands_pristine_command.rb
index c40d32ae61..4ebe1efecb 100644
--- a/test/rubygems/test_gem_commands_pristine_command.rb
+++ b/test/rubygems/test_gem_commands_pristine_command.rb
@@ -160,9 +160,11 @@ class TestGemCommandsPristineCommand < Gem::TestCase
 
     ruby_exec = sprintf Gem.default_exec_format, 'ruby'
 
-    bin_env = win_platform? ? "" : %w(/usr/bin/env /bin/env).find {|f| File.executable?(f) }
-
-    assert_match %r%\A#!\s*#{bin_env} #{ruby_exec}%, File.read(gem_exec)
+    if win_platform?
+      assert_match %r%\A#!\s*#{ruby_exec}%, File.read(gem_exec)
+    else
+      assert_match %r%\A#!\s*/usr/bin/env #{ruby_exec}%, File.read(gem_exec)
+    end
   end
 
   def test_execute_extensions_explicit
diff --git a/test/rubygems/test_gem_commands_setup_command.rb b/test/rubygems/test_gem_commands_setup_command.rb
index d2e04d760b..30daa82d61 100644
--- a/test/rubygems/test_gem_commands_setup_command.rb
+++ b/test/rubygems/test_gem_commands_setup_command.rb
@@ -107,7 +107,7 @@ class TestGemCommandsSetupCommand < Gem::TestCase
     end
     install_gem gem
 
-    File.join Gem.plugins_dir, "#{name}_plugin.rb"
+    File.join Gem.plugindir, "#{name}_plugin.rb"
   end
 
   def test_execute_regenerate_binstubs
@@ -160,6 +160,18 @@ class TestGemCommandsSetupCommand < Gem::TestCase
     assert_equal "I changed it!\n", File.read(gem_plugin_path)
   end
 
+  def test_execute_regenerate_plugins_creates_plugins_dir_if_not_there
+    gem_plugin_path = gem_install_with_plugin 'a'
+
+    # Simulate gem installed with an older rubygems without a plugins layout
+    FileUtils.rm_rf Gem.plugindir
+
+    @cmd.options[:document] = []
+    @cmd.execute
+
+    assert_match %r{\Arequire}, File.read(gem_plugin_path)
+  end
+
   def test_execute_informs_about_installed_executables
     use_ui @ui do
       @cmd.execute
@@ -184,11 +196,15 @@ class TestGemCommandsSetupCommand < Gem::TestCase
 
     ruby_exec = sprintf Gem.default_exec_format, 'ruby'
 
-    bin_env = win_platform? ? "" : %w(/usr/bin/env /bin/env).find {|f| File.executable?(f) }
-
-    assert_match %r%\A#!#{bin_env}\s*#{ruby_exec}%, File.read(default_gem_bin_path)
-    assert_match %r%\A#!#{bin_env}\s*#{ruby_exec}%, File.read(default_bundle_bin_path)
-    assert_match %r%\A#!#{bin_env}\s*#{ruby_exec}%, File.read(gem_bin_path)
+    if Gem.win_platform?
+      assert_match %r%\A#!\s*#{ruby_exec}%, File.read(default_gem_bin_path)
+      assert_match %r%\A#!\s*#{ruby_exec}%, File.read(default_bundle_bin_path)
+      assert_match %r%\A#!\s*#{ruby_exec}%, File.read(gem_bin_path)
+    else
+      assert_match %r%\A#!/usr/bin/env #{ruby_exec}%, File.read(default_gem_bin_path)
+      assert_match %r%\A#!/usr/bin/env #{ruby_exec}%, File.read(default_bundle_bin_path)
+      assert_match %r%\A#!/usr/bin/env #{ruby_exec}%, File.read(gem_bin_path)
+    end
   end
 
   def test_pem_files_in
diff --git a/test/rubygems/test_gem_commands_update_command.rb b/test/rubygems/test_gem_commands_update_command.rb
index 340c658b9d..efaa621634 100644
--- a/test/rubygems/test_gem_commands_update_command.rb
+++ b/test/rubygems/test_gem_commands_update_command.rb
@@ -169,12 +169,12 @@ class TestGemCommandsUpdateCommand < Gem::TestCase
     @cmd.options[:args]          = []
     @cmd.options[:system]        = "3.1"
 
-    FileUtils.mkdir_p Gem.plugins_dir
-    write_file File.join(Gem.plugins_dir, 'a_plugin.rb')
+    FileUtils.mkdir_p Gem.plugindir
+    write_file File.join(Gem.plugindir, 'a_plugin.rb')
 
     @cmd.execute
 
-    refute_path_exists Gem.plugins_dir, "Plugins folder not removed when updating rubygems to pre-3.2"
+    refute_path_exists Gem.plugindir, "Plugins folder not removed when updating rubygems to pre-3.2"
   end
 
   def test_execute_system_specific_newer_than_or_equal_to_3_2_leaves_plugins_dir_alone
@@ -187,13 +187,13 @@ class TestGemCommandsUpdateCommand < Gem::TestCase
     @cmd.options[:args]          = []
     @cmd.options[:system]        = "3.2"
 
-    FileUtils.mkdir_p Gem.plugins_dir
-    plugin_file = File.join(Gem.plugins_dir, 'a_plugin.rb')
+    FileUtils.mkdir_p Gem.plugindir
+    plugin_file = File.join(Gem.plugindir, 'a_plugin.rb')
     write_file plugin_file
 
     @cmd.execute
 
-    assert_path_exists Gem.plugins_dir, "Plugin folder removed when updating rubygems to post-3.2"
+    assert_path_exists Gem.plugindir, "Plugin folder removed when updating rubygems to post-3.2"
     assert_path_exists plugin_file, "Plugin removed when updating rubygems to post-3.2"
   end
 
diff --git a/test/rubygems/test_gem_dependency_installer.rb b/test/rubygems/test_gem_dependency_installer.rb
index 487b8290bb..67fdd6bde6 100644
--- a/test/rubygems/test_gem_dependency_installer.rb
+++ b/test/rubygems/test_gem_dependency_installer.rb
@@ -48,69 +48,6 @@ class TestGemDependencyInstaller < Gem::TestCase
     util_reset_gems
   end
 
-  def test_available_set_for_name
-    util_setup_gems
-    p1a, = util_gem 'a', '10.a'
-    util_setup_spec_fetcher p1a, @a1, @a1_pre
-
-    inst = Gem::DependencyInstaller.new
-
-    available = Gem::Deprecate.skip_during do
-      inst.available_set_for 'a', Gem::Requirement.default
-    end
-
-    assert_equal %w[a-1], available.set.map { |s| s.spec.full_name }
-  end
-
-  def test_available_set_for_name_prerelease
-    util_setup_gems
-    p1a, = util_gem 'a', '10.a'
-    util_setup_spec_fetcher p1a, @a1, @a1_pre
-
-    inst = Gem::DependencyInstaller.new :prerelease => true
-
-    available = Gem::Deprecate.skip_during do
-      inst.available_set_for 'a', Gem::Requirement.default
-    end
-
-    assert_equal %w[a-10.a],
-                 available.sorted.map { |s| s.spec.full_name }
-  end
-
-  def test_available_set_for_dep
-    util_setup_gems
-    p1a, = util_gem 'a', '10.a'
-    util_setup_spec_fetcher p1a, @a1, @a1_pre
-
-    inst = Gem::DependencyInstaller.new
-
-    dep = Gem::Dependency.new 'a', Gem::Requirement.default
-
-    available = Gem::Deprecate.skip_during do
-      inst.available_set_for dep, Gem::Requirement.default
-    end
-
-    assert_equal %w[a-1], available.set.map { |s| s.spec.full_name }
-  end
-
-  def test_available_set_for_dep_prerelease
-    util_setup_gems
-    p1a, = util_gem 'a', '10.a'
-    util_setup_spec_fetcher p1a, @a1, @a1_pre
-
-    inst = Gem::DependencyInstaller.new :prerelease => true
-
-    dep = Gem::Dependency.new 'a', Gem::Requirement.default
-    dep.prerelease = true
-
-    available = Gem::Deprecate.skip_during do
-      inst.available_set_for dep, Gem::Requirement.default
-    end
-
-    assert_equal %w[a-10.a],
-                 available.sorted.map { |s| s.spec.full_name }
-  end
-
   def test_install
     util_setup_gems
 
@@ -974,191 +911,6 @@ class TestGemDependencyInstaller < Gem::TestCase
     assert_equal %w[d-2], inst.installed_gems.map { |s| s.full_name }
   end
 
-  def test_find_gems_gems_with_sources
-    util_setup_gems
-
-    inst = Gem::DependencyInstaller.new
-    dep = Gem::Dependency.new 'b', '>= 0'
-
-    Gem::Specification.reset
-
-    set = Gem::Deprecate.skip_during do
-      inst.find_gems_with_sources(dep)
-    end
-
-    assert_kind_of Gem::AvailableSet, set
-
-    s = set.set.first
-
-    assert_equal @b1, s.spec
-    assert_equal Gem::Source.new(@gem_repo), s.source
-  end
-
-  def test_find_spec_by_name_and_version_wildcard
-    util_gem 'a', 1
-    FileUtils.mv 'gems/a-1.gem', @tempdir
-
-    FileUtils.touch 'rdoc.gem'
-
-    inst = Gem::DependencyInstaller.new
-
-    available = Gem::Deprecate.skip_during do
-      inst.find_spec_by_name_and_version('*.gem')
-    end
-
-    assert_equal %w[a-1], available.each_spec.map { |spec| spec.full_name }
-  end
-
-  def test_find_spec_by_name_and_version_wildcard_bad_gem
-    FileUtils.touch 'rdoc.gem'
-
-    inst = Gem::DependencyInstaller.new
-
-    assert_raises Gem::Package::FormatError do
-      Gem::Deprecate.skip_during do
-        inst.find_spec_by_name_and_version '*.gem'
-      end
-    end
-  end
-
-  def test_find_spec_by_name_and_version_bad_gem
-    FileUtils.touch 'rdoc.gem'
-
-    inst = Gem::DependencyInstaller.new
-
-    e = assert_raises Gem::Package::FormatError do
-      Gem::Deprecate.skip_during do
-        inst.find_spec_by_name_and_version 'rdoc.gem'
-      end
-    end
-
-    full_path = File.join @tempdir, 'rdoc.gem'
-    assert_equal "package metadata is missing in #{full_path}", e.message
-  end
-
-  def test_find_spec_by_name_and_version_directory
-    Dir.mkdir 'rdoc'
-
-    inst = Gem::DependencyInstaller.new
-
-    e = assert_raises Gem::SpecificGemNotFoundException do
-      Gem::Deprecate.skip_during do
-        inst.find_spec_by_name_and_version 'rdoc'
-      end
-    end
-
-    assert_equal "Could not find a valid gem 'rdoc' (>= 0) " +
-                 "locally or in a repository",
-                 e.message
-  end
-
-  def test_find_spec_by_name_and_version_file
-    FileUtils.touch 'rdoc'
-
-    inst = Gem::DependencyInstaller.new
-
-    e = assert_raises Gem::SpecificGemNotFoundException do
-      Gem::Deprecate.skip_during do
-        inst.find_spec_by_name_and_version 'rdoc'
-      end
-    end
-
-    assert_equal "Could not find a valid gem 'rdoc' (>= 0) " +
-                 "locally or in a repository",
-                 e.message
-  end
-
-  def test_find_gems_with_sources_local
-    util_setup_gems
-
-    FileUtils.mv @a1_gem, @tempdir
-    inst = Gem::DependencyInstaller.new
-    dep = Gem::Dependency.new 'a', '>= 0'
-    set = nil
-
-    Dir.chdir @tempdir do
-      set = Gem::Deprecate.skip_during do
-        inst.find_gems_with_sources dep
-      end
-    end
-
-    gems = set.sorted
-
-    assert_equal 2, gems.length
-
-    remote, local = gems
-
-    assert_equal 'a-1', local.spec.full_name, 'local spec'
-    assert_equal File.join(@tempdir, @a1.file_name),
-                 local.source.download(local.spec), 'local path'
-
-    assert_equal 'a-1', remote.spec.full_name, 'remote spec'
-    assert_equal Gem::Source.new(@gem_repo), remote.source, 'remote path'
-  end
-
-  def test_find_gems_with_sources_prerelease
-    util_setup_gems
-
-    installer = Gem::DependencyInstaller.new
-
-    dependency = Gem::Dependency.new('a', Gem::Requirement.default)
-
-    set = Gem::Deprecate.skip_during do
-      installer.find_gems_with_sources(dependency)
-    end
-
-    releases = set.all_specs
-
-    assert releases.any? { |s| s.name == 'a' and s.version.to_s == '1' }
-    refute releases.any? { |s| s.name == 'a' and s.version.to_s == '1.a' }
-
-    dependency.prerelease = true
-
-    set = Gem::Deprecate.skip_during do
-      installer.find_gems_with_sources(dependency)
-    end
-
-    prereleases = set.all_specs
-
-    assert_equal [@a1_pre, @a1], prereleases
-  end
-
-  def test_find_gems_with_sources_with_best_only_and_platform
-    util_setup_gems
-    a1_x86_mingw32, = util_gem 'a', '1' do |s|
-      s.platform = 'x86-mingw32'
-    end
-    util_setup_spec_fetcher @a1, a1_x86_mingw32
-    Gem.platforms << Gem::Platform.new('x86-mingw32')
-
-    installer = Gem::DependencyInstaller.new
-
-    dependency = Gem::Dependency.new('a', Gem::Requirement.default)
-
-    set = Gem::Deprecate.skip_during do
-      installer.find_gems_with_sources(dependency, true)
-    end
-
-    releases = set.all_specs
-
-    assert_equal [a1_x86_mingw32], releases
-  end
-
-  def test_find_gems_with_sources_with_bad_source
-    Gem.sources.replace ["http://not-there.nothing"]
-
-    installer = Gem::DependencyInstaller.new
-
-    dep = Gem::Dependency.new('a')
-
-    out = Gem::Deprecate.skip_during do
-      installer.find_gems_with_sources(dep)
-    end
-
-    assert out.empty?
-    assert_kind_of Gem::SourceFetchProblem, installer.errors.first
-  end
-
   def test_resolve_dependencies
     util_setup_gems
 
diff --git a/test/rubygems/test_gem_doctor.rb b/test/rubygems/test_gem_doctor.rb
index 75d406ac88..8ca4798c93 100644
--- a/test/rubygems/test_gem_doctor.rb
+++ b/test/rubygems/test_gem_doctor.rb
@@ -158,8 +158,8 @@ This directory does not appear to be a RubyGems repository, skipping
 
     Gem.use_paths @gemhome.to_s
 
-    FileUtils.mkdir_p Gem.plugins_dir
-    bad_plugin = File.join(Gem.plugins_dir, "a_badly_named_file.rb")
+    FileUtils.mkdir_p Gem.plugindir
+    bad_plugin = File.join(Gem.plugindir, "a_badly_named_file.rb")
     write_file bad_plugin
 
     doctor = Gem::Doctor.new @gemhome
diff --git a/test/rubygems/test_gem_gem_runner.rb b/test/rubygems/test_gem_gem_runner.rb
index b700a333f4..5e4eda0516 100644
--- a/test/rubygems/test_gem_gem_runner.rb
+++ b/test/rubygems/test_gem_gem_runner.rb
@@ -8,6 +8,7 @@ class TestGemGemRunner < Gem::TestCase
 
     require 'rubygems/command'
     @orig_args = Gem::Command.build_args
+    @orig_specific_extra_args = Gem::Command.specific_extra_args_hash.dup
 
     require 'rubygems/gem_runner'
     @runner = Gem::GemRunner.new
@@ -17,6 +18,7 @@ class TestGemGemRunner < Gem::TestCase
     super
 
     Gem::Command.build_args = @orig_args
+    Gem::Command.specific_extra_args_hash = @orig_specific_extra_args
   end
 
   def test_do_configuration
diff --git a/test/rubygems/test_gem_installer.rb b/test/rubygems/test_gem_installer.rb
index 29458dbd4e..9f531d4258 100644
--- a/test/rubygems/test_gem_installer.rb
+++ b/test/rubygems/test_gem_installer.rb
@@ -757,7 +757,7 @@ gem 'other', version
       installer.install
     end
 
-    plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+    plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
 
     FileUtils.rm plugin_path
 
@@ -766,6 +766,25 @@ gem 'other', version
     assert File.exist?(plugin_path), 'plugin not written'
   end
 
+  def test_generate_plugins_with_install_dir
+    spec = quick_gem 'a' do |spec|
+      write_file File.join(@tempdir, 'lib', 'rubygems_plugin.rb') do |io|
+        io.write "puts __FILE__"
+      end
+
+      spec.files += %w[lib/rubygems_plugin.rb]
+    end
+
+    util_build_gem spec
+
+    plugin_path = File.join "#{@gemhome}2", 'plugins', 'a_plugin.rb'
+    installer = util_installer spec, "#{@gemhome}2"
+
+    assert_equal spec, installer.install
+
+    assert File.exist?(plugin_path), 'plugin not written to install_dir'
+  end
+
   def test_keeps_plugins_up_to_date
     # NOTE: version a-2 is already installed by setup hooks
 
@@ -779,7 +798,7 @@ gem 'other', version
         spec.files += %w[lib/rubygems_plugin.rb]
       end.install
 
-      plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+      plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
       refute File.exist?(plugin_path), 'old version installed while newer version without plugin also installed, but plugin written'
 
       util_setup_installer do |spec|
@@ -787,7 +806,7 @@ gem 'other', version
         spec.files += %w[lib/rubygems_plugin.rb]
       end.install
 
-      plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+      plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
       assert File.exist?(plugin_path), 'latest version reinstalled, but plugin not written'
       assert_match %r{\Arequire.*a-2/lib/rubygems_plugin\.rb}, File.read(plugin_path), 'written plugin has incorrect content'
 
@@ -796,7 +815,7 @@ gem 'other', version
         spec.files += %w[lib/rubygems_plugin.rb]
       end.install
 
-      plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+      plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
       assert File.exist?(plugin_path), 'latest version installed, but plugin removed'
       assert_match %r{\Arequire.*a-3/lib/rubygems_plugin\.rb}, File.read(plugin_path), 'written plugin has incorrect content'
 
@@ -808,6 +827,17 @@ gem 'other', version
     end
   end
 
+  def test_generates_plugins_dir_under_install_dir_if_not_there
+    Gem.use_paths "#{@gemhome}2" # Set GEM_HOME to an uninitialized repo
+
+    @spec = util_spec 'a'
+
+    path = Gem::Package.build @spec
+
+    installer = Gem::Installer.at path, :install_dir => "#{@gemhome}3"
+    assert_equal @spec, installer.install
+  end
+
   def test_initialize
     spec = util_spec 'a' do |s|
       s.platform = Gem::Platform.new 'mswin32'
@@ -1794,9 +1824,9 @@ gem 'other', version
 
     shebang = installer.shebang 'executable'
 
-    bin_env = get_bin_env
+    env_shebang = "/usr/bin/env" unless Gem.win_platform?
 
-    assert_equal("#!#{bin_env} #{RbConfig::CONFIG['ruby_install_name']}",
+    assert_equal("#!#{env_shebang} #{RbConfig::CONFIG['ruby_install_name']}",
                  shebang)
   end
 
@@ -1875,18 +1905,10 @@ gem 'other', version
     assert_equal "#!test", shebang
   end
 
-  def get_bin_env
-    if win_platform?
-      ""
-    else
-      %w(/usr/bin/env /bin/env).find {|f| File.executable?(f) }
-    end
-  end
-
   def test_shebang_custom_with_expands
     installer = setup_base_installer
 
-    bin_env = get_bin_env
+    bin_env = win_platform? ? '' : '/usr/bin/env'
     conf = Gem::ConfigFile.new []
     conf[:custom_shebang] = '1 $env 2 $ruby 3 $exec 4 $name'
 
@@ -1902,7 +1924,7 @@ gem 'other', version
   def test_shebang_custom_with_expands_and_arguments
     installer = setup_base_installer
 
-    bin_env = get_bin_env
+    bin_env = win_platform? ? '' : '/usr/bin/env'
     conf = Gem::ConfigFile.new []
     conf[:custom_shebang] = '1 $env 2 $ruby 3 $exec'
 
@@ -2130,6 +2152,16 @@ gem 'other', version
     assert_kind_of(Gem::Package, installer.package)
   end
 
+  def test_gem_attribute
+    gem = quick_gem 'c' do |spec|
+      util_make_exec spec, '#!/usr/bin/ruby', 'exe'
+    end
+
+    installer = util_installer(gem, @gemhome)
+    assert_respond_to(installer, :gem)
+    assert_kind_of(String, installer.gem)
+  end
+
   def old_ruby_required(requirement)
     spec = util_spec 'old_ruby_required', '1' do |s|
       s.required_ruby_version = requirement
diff --git a/test/rubygems/test_gem_package.rb b/test/rubygems/test_gem_package.rb
index 5da247e141..64ceda39b2 100644
--- a/test/rubygems/test_gem_package.rb
+++ b/test/rubygems/test_gem_package.rb
@@ -106,7 +106,7 @@ class TestGemPackage < Gem::Package::TarTestCase
     assert_equal expected, YAML.load(checksums)
   end
 
-  def test_build_time_source_date_epoch
+  def test_build_time_uses_source_date_epoch
     epoch = ENV["SOURCE_DATE_EPOCH"]
     ENV["SOURCE_DATE_EPOCH"] = "123456789"
 
@@ -124,12 +124,10 @@ class TestGemPackage < Gem::Package::TarTestCase
     ENV["SOURCE_DATE_EPOCH"] = epoch
   end
 
-  def test_build_time_source_date_epoch_automatically_set
+  def test_build_time_without_source_date_epoch
     epoch = ENV["SOURCE_DATE_EPOCH"]
     ENV["SOURCE_DATE_EPOCH"] = nil
 
-    start_time = Time.now.utc.to_i
-
     spec = Gem::Specification.new 'build', '1'
     spec.summary = 'build'
     spec.authors = 'build'
@@ -138,14 +136,11 @@ class TestGemPackage < Gem::Package::TarTestCase
 
     package = Gem::Package.new spec.file_name
 
-    end_time = Time.now.utc.to_i
-
     assert_kind_of Time, package.build_time
 
     build_time = package.build_time.to_i
 
-    assert_operator(start_time, :<=, build_time)
-    assert_operator(build_time, :<=, end_time)
+    assert_equal Gem.source_date_epoch.to_i, build_time
   ensure
     ENV["SOURCE_DATE_EPOCH"] = epoch
   end
diff --git a/test/rubygems/test_gem_package_tar_writer.rb b/test/rubygems/test_gem_package_tar_writer.rb
index 81661da45a..903d681c7e 100644
--- a/test/rubygems/test_gem_package_tar_writer.rb
+++ b/test/rubygems/test_gem_package_tar_writer.rb
@@ -8,6 +8,11 @@ class TestGemPackageTarWriter < Gem::Package::TarTestCase
   def setup
     super
 
+    # Setting `@default_source_date_epoch` to `nil` effectively resets the
+    # value used for `Gem.source_date_epoch` whenever `$SOURCE_DATE_EPOCH`
+    # is not set.
+    Gem.instance_variable_set(:'@default_source_date_epoch', nil)
+
     @data = 'abcde12345'
     @io = TempIO.new
     @tar_writer = Gem::Package::TarWriter.new @io
diff --git a/test/rubygems/test_gem_remote_fetcher.rb b/test/rubygems/test_gem_remote_fetcher.rb
index 55278afa4e..4df9180944 100644
--- a/test/rubygems/test_gem_remote_fetcher.rb
+++ b/test/rubygems/test_gem_remote_fetcher.rb
@@ -897,8 +897,6 @@ PeIQQkFng2VVot/WAQbv3ePqWq07g1BBcwIBAg==
   end
 
   def test_ssl_client_cert_auth_connection
-    skip 'openssl in jruby fails' if java_platform?
-
     ssl_server = self.class.start_ssl_server({
       :SSLVerifyClient =>
         OpenSSL::SSL::VERIFY_PEER | OpenSSL::SSL::VERIFY_FAIL_IF_NO_PEER_CERT})
diff --git a/test/rubygems/test_gem_spec_fetcher.rb b/test/rubygems/test_gem_spec_fetcher.rb
index 99862ce871..5259e62ccc 100644
--- a/test/rubygems/test_gem_spec_fetcher.rb
+++ b/test/rubygems/test_gem_spec_fetcher.rb
@@ -173,10 +173,19 @@ class TestGemSpecFetcher < Gem::TestCase
     spec_fetcher do|fetcher|
       fetcher.spec 'example', 1
       fetcher.spec 'other-example', 1
+      fetcher.spec 'examp', 1
     end
 
-    suggestions = @sf.suggest_gems_from_name('examplw')
+    suggestions = @sf.suggest_gems_from_name('examplw', type = :latest, num_results = 1)
     assert_equal ['example'], suggestions
+
+    suggestions = @sf.suggest_gems_from_name('other')
+    assert_equal ['other-example'], suggestions
+
+    suggestions = @sf.suggest_gems_from_name('exam')
+    assert suggestions.any? { ['examp'] }
+    assert suggestions.any? { ['example'] }
+    assert suggestions.any? { ['other-example'] }
   end
 
   def test_suggest_gems_from_name_prerelease
diff --git a/test/rubygems/test_gem_specification.rb b/test/rubygems/test_gem_specification.rb
index b7df8b71fd..e5833ddfa4 100644
--- a/test/rubygems/test_gem_specification.rb
+++ b/test/rubygems/test_gem_specification.rb
@@ -83,6 +83,11 @@ end
   def setup
     super
 
+    # Setting `@default_source_date_epoch` to `nil` effectively resets the
+    # value used for `Gem.source_date_epoch` whenever `$SOURCE_DATE_EPOCH`
+    # is not set.
+    Gem.instance_variable_set(:'@default_source_date_epoch', nil)
+
     @a1 = util_spec 'a', '1' do |s|
       s.executable = 'exec'
       s.test_file = 'test/suite.rb'
diff --git a/test/rubygems/test_gem_uninstaller.rb b/test/rubygems/test_gem_uninstaller.rb
index df8dfd9a95..fc330a6040 100644
--- a/test/rubygems/test_gem_uninstaller.rb
+++ b/test/rubygems/test_gem_uninstaller.rb
@@ -178,7 +178,7 @@ class TestGemUninstaller < Gem::InstallerTestCase
 
     Gem::Installer.at(Gem::Package.build(@spec)).install
 
-    plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+    plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
     assert File.exist?(plugin_path), 'plugin not written'
 
     Gem::Uninstaller.new(nil).remove_plugins @spec
@@ -186,6 +186,24 @@ class TestGemUninstaller < Gem::InstallerTestCase
     refute File.exist?(plugin_path), 'plugin not removed'
   end
 
+  def test_remove_plugins_with_install_dir
+    write_file File.join(@tempdir, 'lib', 'rubygems_plugin.rb') do |io|
+      io.write "puts __FILE__"
+    end
+
+    @spec.files += %w[lib/rubygems_plugin.rb]
+
+    Gem::Installer.at(Gem::Package.build(@spec)).install
+
+    plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
+    assert File.exist?(plugin_path), 'plugin not written'
+
+    Dir.mkdir "#{@gemhome}2"
+    Gem::Uninstaller.new(nil, :install_dir => "#{@gemhome}2").remove_plugins @spec
+
+    assert File.exist?(plugin_path), 'plugin unintentionally removed'
+  end
+
   def test_regenerate_plugins_for
     write_file File.join(@tempdir, 'lib', 'rubygems_plugin.rb') do |io|
       io.write "puts __FILE__"
@@ -195,11 +213,11 @@ class TestGemUninstaller < Gem::InstallerTestCase
 
     Gem::Installer.at(Gem::Package.build(@spec)).install
 
-    plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+    plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
     assert File.exist?(plugin_path), 'plugin not written'
 
     FileUtils.rm plugin_path
-    Gem::Uninstaller.new(nil).regenerate_plugins_for @spec
+    Gem::Uninstaller.new(nil).regenerate_plugins_for @spec, Gem.plugindir
 
     assert File.exist?(plugin_path), 'plugin not regenerated'
   end
@@ -611,7 +629,7 @@ create_makefile '#{@spec.name}'
       io.write "puts __FILE__"
     end
 
-    plugin_path = File.join Gem.plugins_dir, 'a_plugin.rb'
+    plugin_path = File.join Gem.plugindir, 'a_plugin.rb'
 
     @spec.version = '1'
     Gem::Installer.at(Gem::Package.build(@spec)).install
diff --git a/test/rubygems/test_require.rb b/test/rubygems/test_require.rb
index 49fe7f96c6..67c55416d4 100644
--- a/test/rubygems/test_require.rb
+++ b/test/rubygems/test_require.rb
@@ -120,6 +120,24 @@ class TestGemRequire < Gem::TestCase
     Object.send :remove_const, :HELLO if Object.const_defined? :HELLO
   end
 
+  def test_dash_i_respects_default_library_extension_priority
+    skip "extensions don't quite work on jruby" if Gem.java_platform?
+
+    dash_i_ext_arg = util_install_extension_file('a')
+    dash_i_lib_arg = util_install_ruby_file('a')
+
+    lp = $LOAD_PATH.dup
+
+    begin
+      $LOAD_PATH.unshift dash_i_lib_arg
+      $LOAD_PATH.unshift dash_i_ext_arg
+      assert_require 'a'
+      assert_match(/a\.rb$/, $LOADED_FEATURES.last)
+    ensure
+      $LOAD_PATH.replace lp
+    end
+  end
+
   def test_concurrent_require
     Object.const_set :FILE_ENTERED_LATCH, Latch.new(2)
     Object.const_set :FILE_EXIT_LATCH, Latch.new(1)
@@ -518,15 +536,15 @@ class TestGemRequire < Gem::TestCase
       define_method "test_no_other_behavioral_changes_with_#{prefix.tr(".", "_")}warn" do
         lib = File.realpath("../../../lib", __FILE__)
         Dir.mktmpdir("warn_test") do |dir|
-          File.write(dir + "/main.rb", "warn({x:1}, {y:2}, [])\n")
+          File.write(dir + "/main.rb", "#{prefix}warn({x:1}, {y:2}, [])\n")
           _, err = capture_subprocess_io do
-            system(@@ruby, "-w", "-rpp", "--disable=gems", "-I", lib, "-C", dir, "-I.", "main.rb")
+            system(@@ruby, "-w", "--disable=gems", "-I", lib, "-C", dir, "main.rb")
           end
-          assert_equal("{:x=>1}\n{:y=>2}\n", err)
+          assert_match(/{:x=>1}\n{:y=>2}\n$/, err)
           _, err = capture_subprocess_io do
-            system(@@ruby, "-w", "-rpp", "--enable=gems", "-I", lib, "-C", dir, "-I.", "main.rb")
+            system(@@ruby, "-w", "--enable=gems", "-I", lib, "-C", dir, "main.rb")
           end
-          assert_equal("{:x=>1}\n{:y=>2}\n", err)
+          assert_match(/{:x=>1}\n{:y=>2}\n$/, err)
         end
       end
     end
@@ -541,4 +559,50 @@ class TestGemRequire < Gem::TestCase
     $VERBOSE = old_verbose
   end
 
+  def util_install_extension_file(name)
+    spec = quick_gem name
+    util_build_gem spec
+
+    spec.extensions << "extconf.rb"
+    write_file File.join(@tempdir, "extconf.rb") do |io|
+      io.write <<-RUBY
+        require "mkmf"
+        CONFIG['LDSHARED'] = '$(TOUCH) $@ ||'
+        create_makefile("#{name}")
+      RUBY
+    end
+
+    write_file File.join(@tempdir, "#{name}.c") do |io|
+      io.write <<-C
+        void Init_#{name}() { }
+      C
+    end
+
+    write_file File.join(@tempdir, "depend")
+
+    spec.files += ["extconf.rb", "depend", "#{name}.c"]
+
+    so = File.join(spec.gem_dir, "#{name}.#{RbConfig::CONFIG["DLEXT"]}")
+    refute_path_exists so
+
+    path = Gem::Package.build spec
+    installer = Gem::Installer.at path
+    installer.install
+    assert_path_exists so
+
+    spec.gem_dir
+  end
+
+  def util_install_ruby_file(name)
+    dir_lib = Dir.mktmpdir("test_require_lib", @tempdir)
+    dash_i_lib_arg = File.join dir_lib
+
+    a_rb = File.join dash_i_lib_arg, "#{name}.rb"
+
+    FileUtils.mkdir_p File.dirname a_rb
+    File.open(a_rb, 'w') { |f| f.write "# #{name}.rb" }
+
+    dash_i_lib_arg
+  end
+
 end