Change skeleton test to assert exact file output

Previously, the skeleton test would assert that every file in the
`default_files` list existed. However, since there is no requirement
that a file is added to this list when added to the generator the list
can (and has) become out of sync with the exact generated output.

This commit refactors the skeleton test to gather the full list of files
created by the generator so that it can be compared exactly to the list
of `default_files`. This ensures the generated file list must be updated
when any file is added or removed from the generator. Additionally, by
using array equality the sorting of the `default_files` list is enforced
(it was previously _mostly_ alphabetical, but not fully).

The new skeleton test assertion was written to only assert files instead
of folders for a few reasons:
- asserting that folders exist is redundant if a file exists within a
  folder (and the `default_files` list would be significantly longer
  with all folders)
- any folder generated without any files inside it will not be tracked
  by Git, so other code cannot assume these empty folders exist

Because of these reasons, this patch also includes a change to no longer
generate the `tmp/cache/assets` folder by default. The folder is an
implementation detail of Sprockets and doesn't need any special
treatment in Rails. The `Sprockets::Cache::FileStore` will create the
directory if it does not exist (which it usually won't since `tmp/cache`
is excluded from Git by the `.gitignore`), and the `tmp:cache:clear`
task already clears all subdirectories of `tmp/cache`.

Finally, some tests making assertions about the default output of the
app generator were removed as they have been made redundant by the
improvements to the skeleton test.

Author: skipkayhil

railties/lib/rails/generators/rails/app/app_generator.rb

@@ -257,8 +257,6 @@ def system_test
     def tmp
       empty_directory_with_keep_file "tmp"
       empty_directory_with_keep_file "tmp/pids"
-      empty_directory "tmp/cache"
-      empty_directory "tmp/cache/assets"
     end
 
     def vendor
@@ -461,7 +459,6 @@ def delete_app_assets_if_api_option
         if options[:api]
           remove_dir "app/assets"
           remove_dir "lib/assets"
-          remove_dir "tmp/cache/assets"
         end
       end
 

railties/lib/rails/tasks/tmp.rake

@@ -7,7 +7,7 @@ namespace :tmp do
   tmp_dirs = [ "tmp/cache",
                "tmp/sockets",
                "tmp/pids",
-               "tmp/cache/assets" ]
+             ]
 
   tmp_dirs.each { |d| directory d }
 

railties/test/generators/api_app_generator_test.rb

@@ -177,7 +177,6 @@ def skipped_files
          config/initializers/permissions_policy.rb
          lib/assets
          test/helpers
-         tmp/cache/assets
          public/404.html
          public/422.html
          public/426.html

railties/test/generators/app_generator_test.rb

@@ -5,90 +5,88 @@
 require "generators/shared_generator_tests"
 
 DEFAULT_APP_FILES = %w(
+  .dockerignore
+  .git
   .gitattributes
   .github/dependabot.yml
   .github/workflows/ci.yml
   .gitignore
-  .dockerignore
   .rubocop.yml
   .ruby-version
-  README.md
+  Dockerfile
   Gemfile
+  README.md
   Rakefile
-  Dockerfile
-  config.ru
   app/assets/config/manifest.js
-  app/assets/images
-  app/assets/stylesheets
+  app/assets/images/.keep
   app/assets/stylesheets/application.css
   app/channels/application_cable/channel.rb
   app/channels/application_cable/connection.rb
-  app/controllers
   app/controllers/application_controller.rb
-  app/controllers/concerns
-  app/helpers
+  app/controllers/concerns/.keep
   app/helpers/application_helper.rb
-  app/mailers
+  app/jobs/application_job.rb
   app/mailers/application_mailer.rb
-  app/models
   app/models/application_record.rb
-  app/models/concerns
-  app/jobs
-  app/jobs/application_job.rb
-  app/views/layouts
+  app/models/concerns/.keep
   app/views/layouts/application.html.erb
   app/views/layouts/mailer.html.erb
   app/views/layouts/mailer.text.erb
-  bin/docker-entrypoint
+  app/views/pwa/manifest.json.erb
+  app/views/pwa/service-worker.js
   bin/brakeman
+  bin/docker-entrypoint
   bin/rails
   bin/rake
   bin/rubocop
   bin/setup
+  config.ru
   config/application.rb
   config/boot.rb
   config/cable.yml
+  config/credentials.yml.enc
+  config/database.yml
   config/environment.rb
-  config/environments
   config/environments/development.rb
   config/environments/production.rb
   config/environments/test.rb
-  config/initializers
   config/initializers/assets.rb
   config/initializers/content_security_policy.rb
   config/initializers/enable_yjit.rb
   config/initializers/filter_parameter_logging.rb
   config/initializers/inflections.rb
-  config/locales
+  config/initializers/permissions_policy.rb
   config/locales/en.yml
+  config/master.key
   config/puma.rb
   config/routes.rb
-  config/credentials.yml.enc
   config/storage.yml
-  db
   db/seeds.rb
-  lib
-  lib/tasks
-  lib/assets
-  log
-  public
-  storage
+  lib/assets/.keep
+  lib/tasks/.keep
+  log/.keep
+  public/404.html
+  public/422.html
+  public/426.html
+  public/500.html
+  public/icon.png
+  public/icon.svg
+  public/robots.txt
+  storage/.keep
   test/application_system_test_case.rb
-  test/test_helper.rb
-  test/fixtures
-  test/fixtures/files
   test/channels/application_cable/connection_test.rb
-  test/controllers
-  test/models
-  test/helpers
-  test/mailers
-  test/integration
-  test/system
-  vendor
-  tmp
-  tmp/cache
-  tmp/cache/assets
-  tmp/storage
+  test/controllers/.keep
+  test/fixtures/files/.keep
+  test/helpers/.keep
+  test/integration/.keep
+  test/mailers/.keep
+  test/models/.keep
+  test/system/.keep
+  test/test_helper.rb
+  tmp/.keep
+  tmp/pids/.keep
+  tmp/storage/.keep
+  vendor/.keep
 )
 
 class AppGeneratorTest < Rails::Generators::TestCase
@@ -111,12 +109,6 @@ def test_skip_bundle
     assert_file "Gemfile"
   end
 
-  def test_assets
-    run_generator
-
-    assert_file("app/assets/stylesheets/application.css")
-  end
-
   def test_invalid_javascript_option_raises_an_error
     content = capture(:stderr) { run_generator([destination_root, "-j", "unknown"]) }
     assert_match(/Expected '--javascript' to be one of/, content)
@@ -132,11 +124,6 @@ def test_invalid_css_option_raises_an_error
     assert_match(/Expected '--css' to be one of/, content)
   end
 
-  def test_application_job_file_present
-    run_generator
-    assert_file("app/jobs/application_job.rb")
-  end
-
   def test_invalid_application_name_raises_an_error
     content = capture(:stderr) { run_generator [File.join(destination_root, "43-things")] }
     assert_equal "Invalid application name 43-things. Please give a name which does not start with numbers.\n", content
@@ -183,17 +170,6 @@ def test_application_name_is_detected_if_it_exists_and_app_folder_renamed
     assert_file "#{app_moved_root}/config/environment.rb", /Rails\.application\.initialize!/
   end
 
-  def test_new_application_not_include_api_initializers
-    run_generator
-
-    assert_no_file "config/initializers/cors.rb"
-  end
-
-  def test_new_application_doesnt_need_defaults
-    run_generator
-    assert_empty Dir.glob("config/initializers/new_framework_defaults_*.rb", base: destination_root)
-  end
-
   def test_new_application_load_defaults
     run_generator
     assert_file "config/application.rb", /\s+config\.load_defaults #{Rails::VERSION::STRING.to_f}/

railties/test/generators/shared_generator_tests.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require "find"
 require "shellwords"
 require "env_helpers"
 
@@ -52,6 +53,30 @@ def test_implied_options_with_conflicting_option
   def test_skeleton_is_created
     run_generator
 
+    generated_files_and_folders = []
+
+    Find.find(destination_root) do |absolute_path|
+      next if absolute_path == destination_root
+
+      pathname = Pathname.new(absolute_path)
+      git_folder = pathname.basename.to_s == ".git"
+
+      if git_folder || pathname.file?
+        generated_files_and_folders << pathname
+          .relative_path_from(destination_root)
+          .to_s
+      elsif pathname.directory? && pathname.children.empty?
+        flunk "`#{pathname} was generated but is an empty directory"
+      end
+
+      Find.prune if git_folder
+    end
+
+    # assert differences first for better error messages
+    assert_empty generated_files_and_folders.difference(default_files)
+    assert_empty default_files.difference(generated_files_and_folders)
+    assert_equal generated_files_and_folders.sort, default_files, "The expected list of generated files is not alphabetical"
+
     default_files.each { |path| assert_file path }
   end