1 files changed, 57 insertions, 0 deletions
diff --git a/lib/rubygems/resolver/installed_specification.rb b/lib/rubygems/resolver/installed_specification.rb
new file mode 100644
index 0000000000..8280ae4672
--- /dev/null
+++ b/lib/rubygems/resolver/installed_specification.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+##
+# An InstalledSpecification represents a gem that is already installed
+# locally.
+
+class Gem::Resolver::InstalledSpecification < Gem::Resolver::SpecSpecification
+  def ==(other) # :nodoc:
+    self.class === other &&
+      @set  == other.set &&
+      @spec == other.spec
+  end
+
+  ##
+  # This is a null install as this specification is already installed.
+  # +options+ are ignored.
+
+  def install(options = {})
+    yield nil
+  end
+
+  ##
+  # Returns +true+ if this gem is installable for the current platform.
+
+  def installable_platform?
+    # BACKCOMPAT If the file is coming out of a specified file, then we
+    # ignore the platform. This code can be removed in RG 3.0.
+    return true if @source.is_a? Gem::Source::SpecificFile
+
+    super
+  end
+
+  def pretty_print(q) # :nodoc:
+    q.group 2, "[InstalledSpecification", "]" do
+      q.breakable
+      q.text "name: #{name}"
+
+      q.breakable
+      q.text "version: #{version}"
+
+      q.breakable
+      q.text "platform: #{platform}"
+
+      q.breakable
+      q.text "dependencies:"
+      q.breakable
+      q.pp spec.dependencies
+    end
+  end
+
+  ##
+  # The source for this specification
+
+  def source
+    @source ||= Gem::Source::Installed.new
+  end
+end