Rename authentication generator template files

Prior to this commit, Authentication generator calls to
[Thor::Actions#template][] were passing a second optional argument to
specify the full filename of the destination.

This was necessary because the template files were nested within
`lib/rails/generators/rails/authentication/templates` in a way that did
not reflect their final destinations. For example, the `user.rb` file
was declared in
`lib/rails/generators/rails/authentication/templates/models/user.rb`
instead of
`lib/rails/generators/rails/authentication/templates/app/models/user.rb`
(i.e. `templates/models/user.rb` instead of
`templates/app/models/user.rb`).

This commit nests the files within the `template/` directory under
`app/` when appropriate, which makes the second argument to
`Thor::Actions#template` optional and able to be omitted.

In addition to the file structure changes, this commit utilizes the
[Thor::Actions#inject_into_class][] helper instead of a call to
[Thor::Actions#gsub_file][].

[Thor::Actions#template]: https://www.rubydoc.info/gems/thor/Thor/Actions#template-instance_method
[Thor::Actions#inject_into_class]: https://www.rubydoc.info/gems/thor/Thor%2FActions:inject_into_class
[Thor::Actions#gsub_file]: https://www.rubydoc.info/gems/thor/Thor%2FActions:gsub_file

Author: seanpdoyle

railties/lib/rails/generators/erb/authentication/authentication_generator.rb

@@ -6,9 +6,9 @@ module Erb # :nodoc:
   module Generators # :nodoc:
     class AuthenticationGenerator < Rails::Generators::Base # :nodoc:
       def create_files
-        template "views/passwords/new.html.erb", File.join("app/views/passwords/new.html.erb")
-        template "views/passwords/edit.html.erb", File.join("app/views/passwords/edit.html.erb")
-        template "views/sessions/new.html.erb", File.join("app/views/sessions/new.html.erb")
+        template "app/views/passwords/new.html.erb"
+        template "app/views/passwords/edit.html.erb"
+        template "app/views/sessions/new.html.erb"
       end
     end
   end

railties/lib/rails/generators/erb/authentication/templates/views/passwords/edit.html.erb renamed to railties/lib/rails/generators/erb/authentication/templates/app/views/passwords/edit.html.erb

@@ -11,24 +11,24 @@ class AuthenticationGenerator < Base # :nodoc:
       end
 
       def create_authentication_files
-        template "models/session.rb", File.join("app/models/session.rb")
-        template "models/user.rb", File.join("app/models/user.rb")
-        template "models/current.rb", File.join("app/models/current.rb")
+        template "app/models/session.rb"
+        template "app/models/user.rb"
+        template "app/models/current.rb"
 
-        template "controllers/sessions_controller.rb", File.join("app/controllers/sessions_controller.rb")
-        template "controllers/concerns/authentication.rb", File.join("app/controllers/concerns/authentication.rb")
-        template "controllers/passwords_controller.rb", File.join("app/controllers/passwords_controller.rb")
+        template "app/controllers/sessions_controller.rb"
+        template "app/controllers/concerns/authentication.rb"
+        template "app/controllers/passwords_controller.rb"
 
-        template "mailers/passwords_mailer.rb", File.join("app/mailers/passwords_mailer.rb")
+        template "app/mailers/passwords_mailer.rb"
 
-        template "views/passwords_mailer/reset.html.erb", File.join("app/views/passwords_mailer/reset.html.erb")
-        template "views/passwords_mailer/reset.text.erb", File.join("app/views/passwords_mailer/reset.text.erb")
+        template "app/views/passwords_mailer/reset.html.erb"
+        template "app/views/passwords_mailer/reset.text.erb"
 
-        template "test/mailers/previews/passwords_mailer_preview.rb", File.join("test/mailers/previews/passwords_mailer_preview.rb")
+        template "test/mailers/previews/passwords_mailer_preview.rb"
       end
 
       def configure_application_controller
-        gsub_file "app/controllers/application_controller.rb", /(class ApplicationController < ActionController::Base)/, "\\1\n  include Authentication"
+        inject_into_class "app/controllers/application_controller.rb", "ApplicationController", "  include Authentication\n"
       end
 
       def configure_authentication_routes