Stop creating ApplicationRecord on model generation

When generating models, we created ApplicationRecord in the default
location if no file existed there.  That was annoying for people who
moved it to somewhere else in the autoload path.  At this point, the
vast majority of apps should have either run the upgrade script or
generated a model since upgrading.  For those that haven't the error
message after generating a new model should be helpful:

   NameError: uninitialized constant ApplicationRecord

To ease friction in that case, this also adds a generator for
ApplicationRecord.

6 files changed, 35 insertions, 34 deletions

diff --git a/railties/lib/rails/generators/rails/application_record/application_record_generator.rb b/railties/lib/rails/generators/rails/application_record/application_record_generator.rb
new file mode 100644
index 0000000000..f6b6e76b1d
--- /dev/null
+++ b/railties/lib/rails/generators/rails/application_record/application_record_generator.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Rails
+  module Generators
+    class ApplicationRecordGenerator < Base # :nodoc:
+      hook_for :orm, required: true, desc: "ORM to be invoked"
+    end
+  end
+end
diff --git a/railties/test/generators/application_record_generator_test.rb b/railties/test/generators/application_record_generator_test.rb
new file mode 100644
index 0000000000..b734d786c0
--- /dev/null
+++ b/railties/test/generators/application_record_generator_test.rb
@@ -0,0 +1,14 @@
+require "generators/generators_test_helper"
+require "rails/generators/rails/application_record/application_record_generator"
+
+class ApplicationRecordGeneratorTest < Rails::Generators::TestCase
+  include GeneratorsTestHelper
+
+  def test_application_record_skeleton_is_created
+    run_generator
+    assert_file "app/models/application_record.rb" do |record|
+      assert_match(/class ApplicationRecord < ActiveRecord::Base/, record)
+      assert_match(/self\.abstract_class = true/, record)
+    end
+  end
+end
diff --git a/railties/test/generators/model_generator_test.rb b/railties/test/generators/model_generator_test.rb
index f41969fc46..651713d3c0 100644
--- a/railties/test/generators/model_generator_test.rb
+++ b/railties/test/generators/model_generator_test.rb
@@ -6,14 +6,6 @@ class ModelGeneratorTest < Rails::Generators::TestCase
   include GeneratorsTestHelper
   arguments %w(Account name:string age:integer)
 
-  def test_application_record_skeleton_is_created
-    run_generator
-    assert_file "app/models/application_record.rb" do |record|
-      assert_match(/class ApplicationRecord < ActiveRecord::Base/, record)
-      assert_match(/self\.abstract_class = true/, record)
-    end
-  end
-
   def test_help_shows_invoked_generators_options
     content = run_generator ["--help"]
     assert_match(/ActiveRecord options:/, content)
@@ -43,17 +35,6 @@ class ModelGeneratorTest < Rails::Generators::TestCase
     assert_no_migration "db/migrate/create_accounts.rb"
   end
 
-  def test_model_with_existent_application_record
-    mkdir_p "#{destination_root}/app/models"
-    touch "#{destination_root}/app/models/application_record.rb"
-
-    Dir.chdir(destination_root) do
-      run_generator ["account"]
-    end
-
-    assert_file "app/models/account.rb", /class Account < ApplicationRecord/
-  end
-
   def test_plural_names_are_singularized
     content = run_generator ["accounts".freeze]
     assert_file "app/models/account.rb", /class Account < ApplicationRecord/
diff --git a/railties/test/generators/namespaced_generators_test.rb b/railties/test/generators/namespaced_generators_test.rb
index 1caabbe6b1..9315a1b9da 100644
--- a/railties/test/generators/namespaced_generators_test.rb
+++ b/railties/test/generators/namespaced_generators_test.rb
@@ -3,6 +3,7 @@ require "rails/generators/rails/controller/controller_generator"
 require "rails/generators/rails/model/model_generator"
 require "rails/generators/mailer/mailer_generator"
 require "rails/generators/rails/scaffold/scaffold_generator"
+require "rails/generators/rails/application_record/application_record_generator"
 
 class NamespacedGeneratorTestCase < Rails::Generators::TestCase
   include GeneratorsTestHelper
@@ -421,3 +422,13 @@ class NamespacedScaffoldGeneratorTest < NamespacedGeneratorTestCase
                 /module TestApp\n  class Admin::RolesControllerTest < ActionDispatch::IntegrationTest/
   end
 end
+
+class NamespacedApplicationRecordGeneratorTest < NamespacedGeneratorTestCase
+  include GeneratorsTestHelper
+  tests Rails::Generators::ApplicationRecordGenerator
+
+  def test_adds_namespace_to_application_record
+    run_generator
+    assert_file "app/models/test_app/application_record.rb", /module TestApp/, /  class ApplicationRecord < ActiveRecord::Base/
+  end
+end
diff --git a/railties/test/generators/plugin_generator_test.rb b/railties/test/generators/plugin_generator_test.rb
index f8512f9157..e8372dea47 100644
--- a/railties/test/generators/plugin_generator_test.rb
+++ b/railties/test/generators/plugin_generator_test.rb
@@ -679,20 +679,6 @@ class PluginGeneratorTest < Rails::Generators::TestCase
     assert_file "app/models/bukkits/article.rb", /class Article < ApplicationRecord/
   end
 
-  def test_generate_application_record_when_does_not_exist_in_mountable_engine
-    run_generator [destination_root, "--mountable"]
-    FileUtils.rm "#{destination_root}/app/models/bukkits/application_record.rb"
-    capture(:stdout) do
-      `#{destination_root}/bin/rails g model article`
-    end
-
-    assert_file "#{destination_root}/app/models/bukkits/application_record.rb" do |record|
-      assert_match(/module Bukkits/, record)
-      assert_match(/class ApplicationRecord < ActiveRecord::Base/, record)
-      assert_match(/self\.abstract_class = true/, record)
-    end
-  end
-
   def test_generate_application_mailer_when_does_not_exist_in_mountable_engine
     run_generator [destination_root, "--mountable"]
     FileUtils.rm "#{destination_root}/app/mailers/bukkits/application_mailer.rb"
diff --git a/railties/test/generators_test.rb b/railties/test/generators_test.rb
index e07627f36d..5063e864ca 100644
--- a/railties/test/generators_test.rb
+++ b/railties/test/generators_test.rb
@@ -124,7 +124,7 @@ class GeneratorsTest < Rails::Generators::TestCase
 
   def test_rails_generators_help_does_not_include_app_nor_plugin_new
     output = capture(:stdout) { Rails::Generators.help }
-    assert_no_match(/app/, output)
+    assert_no_match(/app\W/, output)
     assert_no_match(/[^:]plugin/, output)
   end