Make Rails engine path check more specific

Author: vinistock

lib/tapioca/static/symbol_loader.rb

@@ -22,7 +22,7 @@ def payload_symbols
         sig { params(gem: Gemfile::GemSpec).returns(T::Set[String]) }
         def engine_symbols(gem)
           gem_engine = engines.find do |engine|
-            gem.contains_path?(engine.config.root.to_s)
+            gem.full_gem_path == engine.config.root.to_s
           end
 
           return Set.new unless gem_engine

spec/tapioca/cli/gem_spec.rb

@@ -1505,6 +1505,63 @@ class Application < Rails::Application
           assert_empty_stderr(result)
           assert_success_status(result)
         end
+
+        it "properly filters eager loaded Rails engines when gem is installed from git source" do
+          # When Rails is installed through a release version, each gem contained inside `rails` is placed in a
+          # different sibling directory. However, when Rails is installed through a git source, all gems are placed
+          # nested under the Rails directory. When we check if an engine belongs to a gem, we need to take that into
+          # account to avoid placing symbols that do not belong to the Rails RBI inside of it
+          #
+          # Example of path for git installed Rails:
+          # /Users/me/.gem/ruby/3.3.0/bundler/gems/rails-e3ea4c74124f/
+          # /Users/me/.gem/ruby/3.3.0/bundler/gems/rails-e3ea4c74124f/activestorage
+          # /Users/me/.gem/ruby/3.3.0/bundler/gems/rails-e3ea4c74124f/actionmailbox
+          #
+          # The engines defined by `activestorage` and `actionmailbox` should not be placed in the Rails RBI. They
+          # belong in their own respective RBIs.
+          #
+          # Note that this problem only happens if another gem somehow eager loads the engines. By default, Rails
+          # would've not loaded those classes and they would have not been placed in the Rails RBI.
+
+          @project.write_gemfile!(<<~GEMFILE, append: true)
+            gem("rails", git: "https://github.com/rails/rails", branch: "main")
+          GEMFILE
+
+          # Create a gem that eager loads the ActionMailbox engine
+          gem = mock_gem("eager_loader", "1.0.0") do
+            write!("lib/eager_loader.rb", <<~RUBY)
+              require "action_mailbox/engine"
+
+              module EagerLoader
+              end
+            RUBY
+          end
+          @project.require_mock_gem(gem)
+
+          install_result = @project.bundle_install!
+          assert_predicate(install_result, :status, "Bundle install failed\n\n#{install_result.err}")
+
+          result = @project.tapioca("gem rails")
+          assert_empty_stderr(result)
+          assert_success_status(result)
+
+          assert_stdout_includes(result, "Compiled rails")
+          rails_rbi = T.must(Dir.glob("#{@project.absolute_path}/sorbet/rbi/gems/rails@*.rbi").first)
+
+          expected_rbi = <<~RBI
+            # typed: true
+
+            # DO NOT EDIT MANUALLY
+            # This is an autogenerated file for types exported from the `rails` gem.
+            # Please instead update this file by running `bin/tapioca gem rails`.
+
+
+            # THIS IS AN EMPTY RBI FILE.
+            # see https://github.com/Shopify/tapioca#manually-requiring-parts-of-a-gem
+          RBI
+
+          assert_equal(expected_rbi, File.read(rails_rbi))
+        end
       end
 
       describe "verify" do