Authentication generator supports an --api flag (rails#52442)

and the sessions view template has been moved into an erb generator so
that gems like tailwindcss-rails can provide a specialized template.

Author: flavorjones

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

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require "rails/generators/erb"
+
+module Erb # :nodoc:
+  module Generators # :nodoc:
+    class AuthenticationGenerator < Rails::Generators::Base # :nodoc:
+      def create_files
+        template "views/sessions/new.html.erb", File.join("app/views/sessions/new.html.erb")
+      end
+    end
+  end
+end

railties/lib/rails/generators/rails/authentication/templates/views/sessions/new.html.erb renamed to railties/lib/rails/generators/erb/authentication/templates/views/sessions/new.html.erb

@@ -3,15 +3,20 @@
 module Rails
   module Generators
     class AuthenticationGenerator < Base # :nodoc:
+      class_option :api, type: :boolean,
+        desc: "Generate API-only controllers and models, with no view templates"
+
+      hook_for :template_engine, as: :authentication do |template_engine|
+        invoke template_engine unless options.api?
+      end
+
       def create_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 "controllers/sessions_controller.rb", File.join("app/controllers/sessions_controller.rb")
         template "controllers/concerns/authentication.rb", File.join("app/controllers/concerns/authentication.rb")
-
-        template "views/sessions/new.html.erb", File.join("app/views/sessions/new.html.erb")
       end
 
       def configure_application

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

@@ -10,17 +10,18 @@ class AuthenticationGeneratorTest < Rails::Generators::TestCase
   def setup
     Rails.application = TestApp::Application
     Rails.application.config.root = Pathname(destination_root)
+
+    self.class.tests Rails::Generators::AppGenerator
+    run_generator([destination_root])
+
+    self.class.tests Rails::Generators::AuthenticationGenerator
   end
 
   def teardown
     Rails.application = Rails.application.instance
   end
 
   def test_authentication_generator
-    self.class.tests Rails::Generators::AppGenerator
-    run_generator([destination_root])
-
-    self.class.tests Rails::Generators::AuthenticationGenerator
     run_generator
 
     assert_file "app/models/user.rb"
@@ -50,4 +51,35 @@ def test_authentication_generator
       assert_match(/t.string :password_digest, null: false/, content)
     end
   end
+
+  def test_authentication_generator_with_api_flag
+    run_generator(["--api"])
+
+    assert_file "app/models/user.rb"
+    assert_file "app/models/current.rb"
+    assert_file "app/models/session.rb"
+    assert_file "app/controllers/sessions_controller.rb"
+    assert_file "app/controllers/concerns/authentication.rb"
+    assert_no_file "app/views/sessions/new.html.erb"
+
+    assert_file "app/controllers/application_controller.rb" do |content|
+      assert_match(/include Authentication/, content)
+    end
+
+    assert_file "Gemfile" do |content|
+      assert_match(/\ngem "bcrypt"/, content)
+    end
+
+    assert_file "config/routes.rb" do |content|
+      assert_match(/resource :session/, content)
+    end
+
+    assert_migration "db/migrate/create_sessions.rb" do |content|
+      assert_match(/t.references :user, null: false, foreign_key: true/, content)
+    end
+
+    assert_migration "db/migrate/create_users.rb" do |content|
+      assert_match(/t.string :password_digest, null: false/, content)
+    end
+  end
 end