Only load example group modules when they're used

lib/rspec/rails.rb

@@ -1,6 +1,24 @@
 require 'rspec/core'
 require 'rails/version'
 
+module RSpec
+  module Rails
+    autoload :RailsExampleGroup, 'rspec/rails/example/rails_example_group'
+    autoload :ControllerExampleGroup, 'rspec/rails/example/controller_example_group'
+    autoload :HelperExampleGroup, 'rspec/rails/example/helper_example_group'
+    autoload :ModelExampleGroup, 'rspec/rails/example/model_example_group'
+    autoload :RequestExampleGroup, 'rspec/rails/example/request_example_group'
+    autoload :RoutingExampleGroup, 'rspec/rails/example/routing_example_group'
+    autoload :ViewExampleGroup, 'rspec/rails/example/view_example_group'
+    autoload :FeatureExampleGroup, 'rspec/rails/example/feature_example_group'
+    autoload :SystemExampleGroup, 'rspec/rails/example/system_example_group'
+    autoload :MailerExampleGroup, 'rspec/rails/example/mailer_example_group'
+    autoload :JobExampleGroup, 'rspec/rails/example/job_example_group'
+    autoload :ChannelExampleGroup, 'rspec/rails/example/channel_example_group'
+    autoload :MailboxExampleGroup, 'rspec/rails/example/mailbox_example_group'
+  end
+end
+
 # Load any of our adapters and extensions early in the process
 require 'rspec/rails/adapters'
 require 'rspec/rails/extensions'
@@ -11,8 +29,10 @@
 require 'rspec/rails/fixture_support'
 require 'rspec/rails/file_fixture_support'
 require 'rspec/rails/fixture_file_upload_support'
-require 'rspec/rails/example'
 require 'rspec/rails/vendor/capybara'
 require 'rspec/rails/configuration'
 require 'rspec/rails/active_record'
 require 'rspec/rails/feature_check'
+require 'rspec/rails/view_assigns'
+require 'rspec/rails/view_path_builder'
+require 'rspec/rails/view_spec_methods'

lib/rspec/rails/configuration.rb

@@ -1,3 +1,6 @@
+# minitest was previously always loaded, and users may have come to depend on it.
+require "minitest"
+
 # rubocop: disable Metrics/ModuleLength
 module RSpec
   module Rails
@@ -45,15 +48,40 @@ class Configuration
     #
     # @api private
     def self.add_test_type_configurations(config)
-      config.include RSpec::Rails::ControllerExampleGroup, type: :controller
-      config.include RSpec::Rails::HelperExampleGroup,     type: :helper
-      config.include RSpec::Rails::ModelExampleGroup,      type: :model
-      config.include RSpec::Rails::RequestExampleGroup,    type: :request
-      config.include RSpec::Rails::RoutingExampleGroup,    type: :routing
-      config.include RSpec::Rails::ViewExampleGroup,       type: :view
-      config.include RSpec::Rails::FeatureExampleGroup,    type: :feature
+      config.define_derived_metadata(type: :controller) do
+        config.include RSpec::Rails::ControllerExampleGroup, type: :controller
+      end
+
+      config.define_derived_metadata(type: :helper) do
+        config.include RSpec::Rails::HelperExampleGroup, type: :helper
+      end
+
+      config.define_derived_metadata(type: :model) do
+        config.include RSpec::Rails::ModelExampleGroup, type: :model
+      end
+
+      config.define_derived_metadata(type: :request) do
+        config.include RSpec::Rails::RequestExampleGroup, type: :request
+      end
+
+      config.define_derived_metadata(type: :routing) do
+        require "action_controller/test_case"
+        config.include RSpec::Rails::RoutingExampleGroup, type: :routing
+      end
+
+      config.define_derived_metadata(type: :view) do
+        config.include RSpec::Rails::ViewExampleGroup, type: :view
+      end
+
+      config.define_derived_metadata(type: :feature) do
+        config.include RSpec::Rails::FeatureExampleGroup, type: :feature
+      end
+
       config.include RSpec::Rails::Matchers
-      config.include RSpec::Rails::SystemExampleGroup, type: :system
+
+      config.define_derived_metadata(type: :system) do
+        config.include RSpec::Rails::SystemExampleGroup, type: :system
+      end
     end
 
     # @private
@@ -192,27 +220,38 @@ def fixture_path=(path)
 
       if defined?(::Rails::Controller::Testing)
         [:controller, :view, :request].each do |type|
-          config.include ::Rails::Controller::Testing::TestProcess, type: type
-          config.include ::Rails::Controller::Testing::TemplateAssertions, type: type
-          config.include ::Rails::Controller::Testing::Integration, type: type
+          config.define_derived_metadata(type: type) do
+            config.include ::Rails::Controller::Testing::TestProcess, type: type
+            config.include ::Rails::Controller::Testing::TemplateAssertions, type: type
+            config.include ::Rails::Controller::Testing::Integration, type: type
+          end
         end
       end
 
       if RSpec::Rails::FeatureCheck.has_action_mailer?
-        config.include RSpec::Rails::MailerExampleGroup, type: :mailer
+        config.define_derived_metadata(type: :mailer) do
+          config.include RSpec::Rails::MailerExampleGroup, type: :mailer
+        end
+
         config.after { ActionMailer::Base.deliveries.clear }
       end
 
       if RSpec::Rails::FeatureCheck.has_active_job?
-        config.include RSpec::Rails::JobExampleGroup, type: :job
+        config.define_derived_metadata(type: :job) do
+          config.include RSpec::Rails::JobExampleGroup, type: :job
+        end
       end
 
       if RSpec::Rails::FeatureCheck.has_action_cable_testing?
-        config.include RSpec::Rails::ChannelExampleGroup, type: :channel
+        config.define_derived_metadata(type: :channel) do
+          config.include RSpec::Rails::ChannelExampleGroup, type: :channel
+        end
       end
 
       if RSpec::Rails::FeatureCheck.has_action_mailbox?
-        config.include RSpec::Rails::MailboxExampleGroup, type: :mailbox
+        config.define_derived_metadata(type: :mailbox) do
+          config.include RSpec::Rails::MailboxExampleGroup, type: :mailbox
+        end
       end
     end
 

lib/rspec/rails/example.rb

@@ -1,13 +1,3 @@
-require 'rspec/rails/example/rails_example_group'
-require 'rspec/rails/example/controller_example_group'
-require 'rspec/rails/example/request_example_group'
-require 'rspec/rails/example/helper_example_group'
-require 'rspec/rails/example/view_example_group'
-require 'rspec/rails/example/mailer_example_group'
-require 'rspec/rails/example/routing_example_group'
-require 'rspec/rails/example/model_example_group'
-require 'rspec/rails/example/job_example_group'
-require 'rspec/rails/example/feature_example_group'
-require 'rspec/rails/example/system_example_group'
-require 'rspec/rails/example/channel_example_group'
-require 'rspec/rails/example/mailbox_example_group'
+RSpec.warn_deprecation <<~WARNING
+  Requiring rspec/rails/example.rb no longer has any effect, and it will be removed in RSpec Rails 7.
+WARNING

lib/rspec/rails/example/helper_example_group.rb

@@ -1,5 +1,3 @@
-require 'rspec/rails/view_assigns'
-
 module RSpec
   module Rails
     # @api public

lib/rspec/rails/example/view_example_group.rb

@@ -1,7 +1,3 @@
-require 'rspec/rails/view_assigns'
-require 'rspec/rails/view_spec_methods'
-require 'rspec/rails/view_path_builder'
-
 module RSpec
   module Rails
     # @api public

spec/rspec/rails/configuration_spec.rb

@@ -291,6 +291,7 @@ def in_inferring_type_from_location_environment
   end
 
   it "metadata `type: :request` sets up request example groups" do
+    require "rspec/rails/example/request_example_group"
     a_rails_app = double("Rails application")
     the_rails_module = Module.new {
       def self.version; end
@@ -328,6 +329,7 @@ def self.application; end
   end
 
   it "metadata `type: :feature` sets up feature example groups" do
+    require "rspec/rails/example/feature_example_group"
     a_rails_app = double("Rails application")
     the_rails_module = Module.new {
       def self.version; end