Merge pull request rails#46478 from jonathanhefner/app_generator_test-run_generator_and_bundler

Add Bundler helper for `AppGeneratorTest`

Author: jonathanhefner

railties/test/generators/app_generator_test.rb

@@ -825,7 +825,7 @@ def test_no_skip_javascript_option_with_no_skip_javascript_argument
   end
 
   def test_hotwire
-    run_generator [destination_root, "--no-skip-bundle"]
+    run_generator_and_bundler [destination_root]
     assert_gem "turbo-rails"
     assert_gem "stimulus-rails"
     assert_file "app/views/layouts/application.html.erb" do |content|
@@ -848,15 +848,15 @@ def test_skip_hotwire
   end
 
   def test_css_option_with_asset_pipeline_tailwind
-    run_generator [destination_root, "--css", "tailwind", "--no-skip-bundle"]
+    run_generator_and_bundler [destination_root, "--css=tailwind"]
     assert_gem "tailwindcss-rails"
     assert_file "app/views/layouts/application.html.erb" do |content|
       assert_match(/tailwind/, content)
     end
   end
 
   def test_css_option_with_cssbundling_gem
-    run_generator [destination_root, "--css", "postcss", "--no-skip-bundle"]
+    run_generator_and_bundler [destination_root, "--css=postcss"]
     assert_gem "cssbundling-rails"
     assert_file "app/assets/stylesheets/application.postcss.css"
   end
@@ -1068,6 +1068,20 @@ def test_name_option
   end
 
   private
+    def run_generator_and_bundler(args)
+      option_args, positional_args = args.partition { |arg| arg.start_with?("--") }
+      option_args << "--no-skip-bundle"
+      generator(positional_args, option_args)
+
+      # Stub `rails_gemfile_entry` so that Bundler resolves `gem "rails"` to the
+      # current repository instead of searching for an invalid version number
+      # (for a version that hasn't been released yet).
+      rails_gemfile_entry = Rails::Generators::AppBase::GemfileEntry.path("rails", Rails::Generators::RAILS_DEV_PATH)
+      generator.stub(:rails_gemfile_entry, -> { rails_gemfile_entry }) do
+        quietly { run_generator_instance }
+      end
+    end
+
     def run_app_update(app_root = destination_root)
       Dir.chdir(app_root) do
         gemfile_contents = File.read("Gemfile")