Introduce suspenders:testing generator (#1156)

Set up projects for an in-depth test-driven development workflow.

Installs and configures [rspec-rails][],
[action_dispatch-testing-integration-capybara][], [shoulda-matchers][],
[webdrivers][] and [webmock][].

[rspec-rails]: https://github.com/rspec/rspec-rails
[action_dispatch-testing-integration-capybara]: https://github.com/thoughtbot/action_dispatch-testing-integration-capybara
[shoulda-matchers]: https://github.com/thoughtbot/shoulda-matchers
[webdrivers]: https://github.com/titusfortner/webdrivers
[webmock]: https://github.com/bblimke/webmock

## Details

Generate `spec/rails_helper.rb` and `spec/spec_helper.rb` via `rails g rspec:intall`
in an effort to not drift from what RSpec recommends out of the box.

```ruby
#spec/spec_helper.rb
RSpec.configure do |config|
  config.example_status_persistence_file_path = "tmp/rspec_examples.txt"
  config.order = :random

  config.expect_with :rspec do |expectations|
    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
  end

  config.mock_with :rspec do |mocks|
    mocks.verify_partial_doubles = true
  end
  config.shared_context_metadata_behavior = :apply_to_host_groups
end

WebMock.disable_net_connect!(
  allow_localhost: true,
  allow: [
    /(chromedriver|storage).googleapis.com/,
    "googlechromelabs.github.io",
  ]
)
```

The only thing that differs from the existing `spec/rails_helper.rb` configuration is:

```ruby
config.infer_base_class_for_anonymous_controllers = false
```

```ruby
# spec/support/chromedriver.rb

require "selenium/webdriver"

Capybara.register_driver :chrome do |app|
  Capybara::Selenium::Driver.new(app, browser: :chrome)
end

Capybara.register_driver :headless_chrome do |app|
  options = ::Selenium::WebDriver::Chrome::Options.new
  options.headless!
  options.add_argument "--window-size=1680,1050"

  Capybara::Selenium::Driver.new app,
    browser: :chrome,
    options: options
end

Capybara.javascript_driver = :headless_chrome

RSpec.configure do |config|
  config.before(:each, type: :system) do
    driven_by :rack_test
  end

  config.before(:each, type: :system, js: true) do
    driven_by Capybara.javascript_driver
  end
end
```

```ruby
# spec/support/shoulda_matchers.rb

Shoulda::Matchers.configure do |config|
  config.integrate do |with|
    with.test_framework :rspec
    with.library :rails
  end
end
```

```ruby
# spec/support/i18n.rb

RSpec.configure do |config|
  config.include ActionView::Helpers::TranslationHelper
end
```

```ruby
# spec/support/action_mailer.rb

RSpec.configure do |config|
  config.before(:each) do
    ActionMailer::Base.deliveries.clear
  end
end
```

## Notable changes

This commit removes the [formulaic][] dependency. A
follow-up commit could explore creating a separate one-off generator for
this, but for now, we're aiming for the leanest build possible.

[formulaic]: https://github.com/calebhearth/formulaic

NEWS.md

@@ -14,6 +14,7 @@ Unreleased
 * Introduce `suspenders:tasks` generator
 * Introduce `suspenders:db:migrate` task
 * Introduce `suspenders:email` generator
+* Introduce `suspenders:testing` generator
 
 20230113.0 (January, 13, 2023)
 

README.md

@@ -176,6 +176,20 @@ Configures `default_url_options` in `test` and `development`.
 bin/rails g suspenders:email
 ```
 
+### Testing
+
+Set up the project for an in-depth test-driven development workflow.
+
+Installs and configures [rspec-rails][],
+[action_dispatch-testing-integration-capybara][], [shoulda-matchers][],
+[webdrivers][] and [webmock][].
+
+[rspec-rails]: https://github.com/rspec/rspec-rails
+[action_dispatch-testing-integration-capybara]: https://github.com/thoughtbot/action_dispatch-testing-integration-capybara
+[shoulda-matchers]: https://github.com/thoughtbot/shoulda-matchers
+[webdrivers]: https://github.com/titusfortner/webdrivers
+[webmock]: https://github.com/bblimke/webmock
+
 ## Contributing
 
 See the [CONTRIBUTING] document.

lib/generators/suspenders/testing_generator.rb

@@ -0,0 +1,84 @@
+module Suspenders
+  module Generators
+    class TestingGenerator < Rails::Generators::Base
+      source_root File.expand_path("../../templates/testing", __FILE__)
+      desc "Set up the project for an in-depth test-driven development workflow."
+
+      def add_gems
+        gem_group :development, :test do
+          gem "rspec-rails", "~> 6.1.0"
+        end
+
+        gem_group :test do
+          gem "action_dispatch-testing-integration-capybara",
+            github: "thoughtbot/action_dispatch-testing-integration-capybara", tag: "v0.1.0",
+            require: "action_dispatch/testing/integration/capybara/rspec"
+          gem "shoulda-matchers", "~> 6.0"
+          gem "webdrivers"
+          gem "webmock"
+        end
+
+        Bundler.with_unbundled_env { run "bundle install" }
+      end
+
+      def run_rspec_installation_script
+        rails_command "generate rspec:install"
+      end
+
+      def modify_rails_helper
+        insert_into_file "spec/rails_helper.rb",
+          "\s\sconfig.infer_base_class_for_anonymous_controllers = false\n",
+          after: "RSpec.configure do |config|\n"
+      end
+
+      def modify_spec_helper
+        persistence_file_path = "\s\sconfig.example_status_persistence_file_path = \"tmp/rspec_examples.txt\"\n"
+        order = "\s\sconfig.order = :random\n\n"
+        webmock_config = <<~RUBY
+
+          WebMock.disable_net_connect!(
+            allow_localhost: true,
+            allow: [
+              /(chromedriver|storage).googleapis.com/,
+              "googlechromelabs.github.io",
+            ]
+          )
+        RUBY
+
+        insert_into_file "spec/spec_helper.rb",
+          persistence_file_path + order,
+          after: "RSpec.configure do |config|\n"
+
+        insert_into_file "spec/spec_helper.rb", "require \"webmock/rspec\"\n\n", before: "RSpec.configure do |config|"
+        insert_into_file "spec/spec_helper.rb", webmock_config
+      end
+
+      def create_system_spec_dir
+        empty_directory "spec/system"
+        create_file "spec/system/.gitkeep"
+      end
+
+      def configure_chromedriver
+        copy_file "chromedriver.rb", "spec/support/chromedriver.rb"
+      end
+
+      def configure_i18n_helper
+        copy_file "i18n.rb", "spec/support/i18n.rb"
+      end
+
+      def configure_shoulda_matchers
+        copy_file "shoulda_matchers.rb", "spec/support/shoulda_matchers.rb"
+      end
+
+      def configure_action_mailer_helpers
+        # https://guides.rubyonrails.org/testing.html#the-basic-test-case
+        #
+        # The ActionMailer::Base.deliveries array is only reset automatically in
+        # ActionMailer::TestCase and ActionDispatch::IntegrationTest tests. If
+        # you want to have a clean slate outside these test cases, you can reset
+        # it manually with: ActionMailer::Base.deliveries.clear
+        copy_file "action_mailer.rb", "spec/support/action_mailer.rb"
+      end
+    end
+  end
+end

lib/generators/templates/testing/action_mailer.rb

@@ -0,0 +1,5 @@
+RSpec.configure do |config|
+  config.before(:each) do
+    ActionMailer::Base.deliveries.clear
+  end
+end

lib/generators/templates/testing/chromedriver.rb

@@ -0,0 +1,27 @@
+require "selenium/webdriver"
+
+Capybara.register_driver :chrome do |app|
+  Capybara::Selenium::Driver.new(app, browser: :chrome)
+end
+
+Capybara.register_driver :headless_chrome do |app|
+  options = ::Selenium::WebDriver::Chrome::Options.new
+  options.headless!
+  options.add_argument "--window-size=1680,1050"
+
+  Capybara::Selenium::Driver.new app,
+    browser: :chrome,
+    options: options
+end
+
+Capybara.javascript_driver = :headless_chrome
+
+RSpec.configure do |config|
+  config.before(:each, type: :system) do
+    driven_by :rack_test
+  end
+
+  config.before(:each, type: :system, js: true) do
+    driven_by Capybara.javascript_driver
+  end
+end

lib/generators/templates/testing/i18n.rb

@@ -0,0 +1,3 @@
+RSpec.configure do |config|
+  config.include ActionView::Helpers::TranslationHelper
+end

lib/generators/templates/testing/shoulda_matchers.rb

@@ -0,0 +1,6 @@
+Shoulda::Matchers.configure do |config|
+  config.integrate do |with|
+    with.test_framework :rspec
+    with.library :rails
+  end
+end