[rubygems/rubygems] Add a warning in an edge case of using `gemspec` DSL

If a Gemfile duplicates a development dependency also defined in a local
gemspec with a different requirement, the requirement in the local
gemspec will be silently ignored.

This surprised me.

I think we should either:

* Make sure both requirements are considered, like it happens for
  runtime dependencies (I added a spec to illustrate the current behavior
  here).

* Add a warning that the requirement in the gemspec will be ignored.

I think the former is slightly preferable, but it may cause some
bundle's that previously resolve to no longer resolver.

I went with the latter but the more I think about it, the more this
seems like it should behave like the former.

https://github.com/rubygems/rubygems/commit/ad6843972f

1 files changed, 54 insertions, 0 deletions

diff --git a/spec/bundler/commands/install_spec.rb b/spec/bundler/commands/install_spec.rb
index c2f55befc3..4456af2572 100644
--- a/spec/bundler/commands/install_spec.rb
+++ b/spec/bundler/commands/install_spec.rb
@@ -430,6 +430,60 @@ RSpec.describe "bundle install with gem sources" do
       expect(the_bundle).to include_gems("my-private-gem 1.0")
     end
 
+    it "throws a warning if a gem is added once in Gemfile and also inside a gemspec as a development dependency, with different requirements" do
+      build_lib "my-gem", :path => bundled_app do |s|
+        s.add_development_dependency "rubocop", "~> 1.36.0"
+      end
+
+      build_repo4 do
+        build_gem "rubocop", "1.36.0"
+        build_gem "rubocop", "1.37.1"
+      end
+
+      gemfile <<~G
+        source "#{file_uri_for(gem_repo4)}"
+
+        gemspec
+
+        gem "rubocop", group: :development
+      G
+
+      bundle :install
+
+      expect(err).to include("A gemspec development dependency (rubocop, ~> 1.36.0) is being overridden by a Gemfile dependency (rubocop, >= 0).")
+      expect(err).to include("This behaviour may change in the future. Please remove either of them, or make sure they both have the same requirement")
+
+      # This is not the best behavior I believe, it would be better if both
+      # requirements are considered if they are compatible, and a version
+      # satisfying both is chosen. But not sure about changing it right now, so
+      # I went with a warning for the time being.
+      expect(the_bundle).to include_gems("rubocop 1.37.1")
+    end
+
+    it "considers both dependencies for resolution if a gem is added once in Gemfile and also inside a local gemspec as a runtime dependency, with different requirements" do
+      build_lib "my-gem", :path => bundled_app do |s|
+        s.add_dependency "rubocop", "~> 1.36.0"
+      end
+
+      build_repo4 do
+        build_gem "rubocop", "1.36.0"
+        build_gem "rubocop", "1.37.1"
+      end
+
+      gemfile <<~G
+        source "#{file_uri_for(gem_repo4)}"
+
+        gemspec
+
+        gem "rubocop"
+      G
+
+      bundle :install
+
+      expect(err).to be_empty
+      expect(the_bundle).to include_gems("rubocop 1.36.0")
+    end
+
     it "throws an error if a gem is added twice in Gemfile when version of one dependency is not specified" do
       install_gemfile <<-G, :raise_on_error => false
         source "#{file_uri_for(gem_repo2)}"