[rubygems/rubygems] Allow using Gem::Version without loading the rest of rubygems

1b862537a5

lib/rubygems/version.rb

@@ -149,6 +149,15 @@
 # For the last example, single-digit versions are automatically extended with
 # a zero to give a sensible result.
 
+# Our code style opens classes directly without opening the intermediate
+# modules. This works because tha main entrypoint `rubygems.rb`, which defines
+# the root `Gem` module, is usually required first. But in this case we want to
+# allow using `Gem::Version` without loading the rest of rubygems, so we
+# explicit define the `Gem` placeholder module first.
+module Gem; end
+
+require_relative "deprecate"
+
 class Gem::Version
   autoload :Requirement, File.expand_path('requirement', __dir__)
 

test/rubygems/test_project_sanity.rb

@@ -17,4 +17,16 @@ class TestProjectSanity < Gem::TestCase
 
     assert status.success?, err
   end
+
+  def test_require_and_use_rubygems_version
+    err, status = Open3.capture2e(
+      *ruby_with_rubygems_in_load_path,
+      "--disable-gems",
+      "-rrubygems/version",
+      "-e",
+      "Gem::Version.new('2.7.0.preview1') >= Gem::Version.new(RUBY_VERSION)"
+    )
+
+    assert status.success?, err
+  end
 end