Prep for removal of fixture support globally.

This adds metadata to ad-hoc include fixture support for any examples or
groups which may require it. It additionally, includes fixture support
into all default `RailsExampleGroup` modules. This provides the current
functionality for the majority of use cases.

Author: cupakromer

lib/rspec/rails/configuration.rb

@@ -65,10 +65,10 @@ def self.initialize_configuration(config)
       config.add_setting :use_instantiated_fixtures
       config.add_setting :global_fixtures
       config.add_setting :fixture_path
+      config.include RSpec::Rails::FixtureSupport, :use_fixtures
 
-      # TODO: We'll need to create a deprecated module in order to properly
-      #  report to gems / projects which are relying on this being loaded
-      #  globally.
+      # We'll need to create a deprecated module in order to properly report to
+      # gems / projects which are relying on this being loaded globally.
       #
       # See rspec/rspec-rails#1355 for history
       #

lib/rspec/rails/example/rails_example_group.rb

@@ -11,6 +11,7 @@ module RailsExampleGroup
       include RSpec::Rails::MinitestLifecycleAdapter if ::Rails::VERSION::STRING >= '4'
       include RSpec::Rails::MinitestAssertionAdapter
       include RSpec::Rails::Matchers
+      include RSpec::Rails::FixtureSupport
     end
   end
 end

spec/rspec/rails/configuration_spec.rb

@@ -133,6 +133,19 @@ def in_inferring_type_from_location_environment
     include_examples "infers type from location", :feature, "spec/features"
   end
 
+  it "fixture support is included with metadata `:use_fixtures`" do
+    in_sub_process do
+      RSpec.configuration.global_fixtures = [:foo]
+      RSpec.configuration.fixture_path = "custom/path"
+
+      group = RSpec.describe("Arbitrary Description", :use_fixtures)
+
+      expect(group).to respond_to(:fixture_path)
+      expect(group.fixture_path).to eq("custom/path")
+      expect(group.new.respond_to?(:foo, true)).to be(true)
+    end
+  end
+
   it "metadata `:type => :controller` sets up controller example groups" do
     a_controller_class = Class.new
     stub_const "SomeController", a_controller_class