Introduce suspenders:factory_bot generator

Maintains functionally with the [existing generator][] while adding
support for the [default Rails test suite]. With this change, the
generator can be invoked on a Rails application that use RSpec and the
default Rails test suite.

Adds generator which adds a test to lint all Factories in an effort to
improve developer experience.

Additionally, we remove the generation of the `dev:prime` task as we
felt that should be the responsibly of another generator.

[existing generator]: https://github.com/thoughtbot/suspenders/blob/main/lib/suspenders/generators/factories_generator.rb
[default Rails test suite]: https://guides.rubyonrails.org/testing.html

NEWS.md

@@ -1,6 +1,7 @@
 Unreleased
 
 * Remove `suspenders` system executable
+* Introduce `suspenders:factory_bot` generator
 
 20230113.0 (January, 13, 2023)
 

README.md

@@ -21,7 +21,15 @@ end
 
 ## Generators
 
-TODO
+### Factory Bot
+
+Installs and configures [factory_bot_rails]. Supports the [default test suite] and [RSpec].
+
+`./bin/rails g suspenders:factory_bot`
+
+  [factory_bot_rails]: https://github.com/thoughtbot/factory_bot_rails
+  [default test suite]: https://guides.rubyonrails.org/testing.html
+  [RSpec]: https://rspec.info
 
 ## Contributing
 

lib/generators/suspenders/factory_bot_generator.rb

@@ -0,0 +1,69 @@
+module Suspenders
+  module Generators
+    class FactoryBotGenerator < Rails::Generators::Base
+      source_root File.expand_path("../../templates/factory_bot", __FILE__)
+      desc "Installs and configures factory_bot_rails. Supports the default test suite and RSpec."
+
+      def add_factory_bot
+        gem_group :development, :test do
+          gem "factory_bot_rails"
+        end
+
+        Bundler.with_unbundled_env { run "bundle install" }
+      end
+
+      def set_up_factory_bot
+        if default_test_helper_present?
+          insert_into_file Rails.root.join("test/test_helper.rb"), after: "class TestCase" do
+            "\n    include FactoryBot::Syntax::Methods"
+          end
+        elsif rspec_test_helper_present?
+          copy_file "factory_bot_rspec.rb", "spec/support/factory_bot.rb"
+          insert_into_file Rails.root.join("spec/rails_helper.rb") do
+            %(Dir[Rails.root.join("spec/support/**/*.rb")].sort.each { |file| require file })
+          end
+        end
+      end
+
+      def generate_empty_factories_file
+        if default_test_suite?
+          copy_file "factories.rb", "test/factories.rb"
+        elsif rspec_test_suite?
+          copy_file "factories.rb", "spec/factories.rb"
+        end
+      end
+
+      def remove_fixture_definitions
+        if default_test_helper_present?
+          comment_lines "test/test_helper.rb", /fixtures :all/
+        end
+      end
+
+      def create_linting_test
+        if default_test_suite?
+          copy_file "factories_test.rb", "test/factory_bots/factories_test.rb"
+        elsif rspec_test_suite?
+          copy_file "factories_spec.rb", "spec/factory_bots/factories_spec.rb"
+        end
+      end
+
+      private
+
+      def default_test_suite?
+        File.exist? Rails.root.join("test")
+      end
+
+      def rspec_test_suite?
+        File.exist? Rails.root.join("spec")
+      end
+
+      def default_test_helper_present?
+        File.exist? Rails.root.join("test/test_helper.rb")
+      end
+
+      def rspec_test_helper_present?
+        File.exist? Rails.root.join("spec/rails_helper.rb")
+      end
+    end
+  end
+end

lib/generators/templates/factory_bot/factories.rb

@@ -0,0 +1,2 @@
+FactoryBot.define do
+end

lib/generators/templates/factory_bot/factories_spec.rb

@@ -0,0 +1,7 @@
+require "rails_helper"
+
+RSpec.describe "Factories" do
+  it "has valid factoties" do
+    FactoryBot.lint traits: true
+  end
+end

lib/generators/templates/factory_bot/factories_test.rb

@@ -0,0 +1,9 @@
+require "test_helper"
+
+class FactoryBotsTest < ActiveSupport::TestCase
+  class FactoryLintingTest < FactoryBotsTest
+    test "linting of factories" do
+      FactoryBot.lint traits: true
+    end
+  end
+end

lib/generators/templates/factory_bot/factory_bot_rspec.rb

@@ -0,0 +1,5 @@
+FactoryBot.use_parent_strategy = true
+
+RSpec.configure do |config|
+  config.include FactoryBot::Syntax::Methods
+end

test/generators/suspenders/factory_bot_generator_test.rb

@@ -0,0 +1,203 @@
+require "test_helper"
+require "generators/suspenders/factory_bot_generator"
+
+module Suspenders
+  module Generators
+    class FactoryBotGenerator::DefaultTest < Rails::Generators::TestCase
+      include Suspenders::TestHelpers
+
+      tests Suspenders::Generators::FactoryBotGenerator
+      destination Rails.root
+      setup :prepare_destination
+      teardown :restore_destination
+
+      test "generator runs without errors" do
+        assert_nothing_raised do
+          run_generator
+        end
+      end
+
+      test "generator has a description" do
+        description = "Installs and configures factory_bot_rails. Supports the default test suite and RSpec."
+
+        assert_equal description, FactoryBotGenerator.desc
+      end
+
+      test "installs gem with Bundler" do
+        Bundler.stubs(:with_unbundled_env).yields
+        generator.expects(:run).with("bundle install").once
+
+        capture(:stdout) do
+          generator.add_factory_bot
+        end
+      end
+
+      test "removes fixture definitions" do
+        File.open(app_root("test/test_helper.rb"), "w") { _1.write test_helper }
+
+        run_generator
+
+        assert_file app_root("test/test_helper.rb") do |file|
+          assert_match(/# fixtures :all/, file)
+        end
+      end
+
+      test "adds gem to Gemfile" do
+        run_generator
+
+        assert_file app_root("Gemfile") do |file|
+          assert_match(/group :development, :test do\n  gem "factory_bot_rails"\nend/, file)
+        end
+      end
+
+      test "includes syntax methods" do
+        File.open(app_root("test/test_helper.rb"), "w") { _1.write test_helper }
+
+        run_generator
+
+        assert_file app_root("test/test_helper.rb") do |file|
+          assert_match(/class TestCase\n    include FactoryBot::Syntax::Methods/, file)
+        end
+      end
+
+      test "creates definition file" do
+        definition_file = <<~RUBY
+          FactoryBot.define do
+          end
+        RUBY
+
+        run_generator
+
+        assert_file app_root("test/factories.rb") do |file|
+          assert_match definition_file, file
+        end
+      end
+
+      test "creates linting test" do
+        factories_test = <<~RUBY
+          require "test_helper"
+
+          class FactoryBotsTest < ActiveSupport::TestCase
+            class FactoryLintingTest < FactoryBotsTest
+              test "linting of factories" do
+                FactoryBot.lint traits: true
+              end
+            end
+          end
+        RUBY
+
+        run_generator
+
+        assert_file app_root("test/factory_bots/factories_test.rb") do |file|
+          assert_match factories_test, file
+        end
+      end
+
+      private
+
+      def prepare_destination
+        mkdir "test"
+        touch "Gemfile"
+      end
+
+      def restore_destination
+        remove_dir_if_exists "test"
+        remove_file_if_exists "Gemfile"
+        remove_dir_if_exists "lib/tasks"
+      end
+
+      def test_helper
+        <<~RUBY
+          ENV["RAILS_ENV"] ||= "test"
+          require_relative "../config/environment"
+          require "rails/test_help"
+
+          module ActiveSupport
+            class TestCase
+              # Run tests in parallel with specified workers
+              parallelize(workers: :number_of_processors)
+
+              # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
+              fixtures :all
+
+              # Add more helper methods to be used by all tests here...
+            end
+          end
+        RUBY
+      end
+    end
+
+    class FactoryBotGenerator::RSpecTest < Rails::Generators::TestCase
+      include Suspenders::TestHelpers
+
+      tests Suspenders::Generators::FactoryBotGenerator
+      destination Rails.root
+      setup :prepare_destination
+      teardown :restore_destination
+
+      test "includes syntax methods" do
+        touch("spec/rails_helper.rb")
+        factory_bot_config = <<~RUBY
+          FactoryBot.use_parent_strategy = true
+
+          RSpec.configure do |config|
+            config.include FactoryBot::Syntax::Methods
+          end
+        RUBY
+
+        run_generator
+
+        assert_file app_root("spec/support/factory_bot.rb") do |file|
+          assert_match factory_bot_config, file
+        end
+        assert_file app_root("spec/rails_helper.rb") do |file|
+          assert_match(/Dir\[Rails\.root\.join\("spec\/support\/\*\*\/\*\.rb"\)\]\.sort\.each { \|file\| require file }/, file)
+        end
+      end
+
+      test "creates definition file" do
+        definition_file = <<~RUBY
+          FactoryBot.define do
+          end
+        RUBY
+
+        run_generator
+
+        assert_file app_root("spec/factories.rb") do |file|
+          assert_match definition_file, file
+        end
+      end
+
+      test "creates linting test" do
+        factories_spec = <<~RUBY
+          require "rails_helper"
+
+          RSpec.describe "Factories" do
+            it "has valid factoties" do
+              FactoryBot.lint traits: true
+            end
+          end
+        RUBY
+
+        run_generator
+
+        assert_file app_root("spec/factory_bots/factories_spec.rb") do |file|
+          assert_match factories_spec, file
+        end
+      end
+
+      private
+
+      def prepare_destination
+        mkdir "spec"
+        touch "Gemfile"
+      end
+
+      def restore_destination
+        remove_dir_if_exists "spec"
+        remove_file_if_exists "Gemfile"
+        remove_dir_if_exists "lib/tasks"
+      end
+    end
+  end
+end