Get rid of the code poking around RSpec's internals

spec/rspec/rails/example/controller_example_group_spec.rb

@@ -31,7 +31,6 @@ def group_for(klass)
         # before #738 implicit subject definition for controllers caused
         # external methods to take precedence over our let definitions
 
-        with_isolated_config do |config|
         mod = Module.new do
           def my_helper
             "other_value"
@@ -44,7 +43,6 @@ def my_helper
         expect(group.new.my_helper).to eq "my_value"
       end
     end
-    end
 
     context "with explicit subject" do
       it "uses the specified subject instead of the controller" do
@@ -109,11 +107,9 @@ def my_helper
 
       context "when infer_base_class_for_anonymous_controllers is true" do
         around(:example) do |ex|
-          with_isolated_config do |config|
-            config.infer_base_class_for_anonymous_controllers = true
+          RSpec.configuration.infer_base_class_for_anonymous_controllers = true
           ex.run
         end
-        end
 
         it "infers the anonymous controller class" do
           group.controller { }
@@ -129,11 +125,9 @@ def my_helper
 
       context "when infer_base_class_for_anonymous_controllers is false" do
         around(:example) do |ex|
-          with_isolated_config do |config|
-            config.infer_base_class_for_anonymous_controllers = false
+          RSpec.configuration.infer_base_class_for_anonymous_controllers = false
           ex.run
         end
-        end
 
         it "sets the anonymous controller class to ApplicationController" do
           group.controller { }

spec/rspec/rails/example/view_example_group_spec.rb

@@ -249,7 +249,6 @@ def _view; end # Stub method
 
       # Regression test from rspec/rspec-rails#833
       it 'is accessible to configuration-level hooks', pending: pending_only_on_ruby_22_rails_52 do
-        with_isolated_config do
         run_count = 0
         RSpec.configuration.before(:each, type: :view) do
           # `view` is provided from the view example type, and serves to
@@ -265,7 +264,6 @@ def _view; end # Stub method
         expect(run_count).to eq 1
       end
     end
-    end
 
     describe "#template" do
       let(:view_spec) do

spec/spec_helper.rb

@@ -23,6 +23,7 @@ def self.world=(world)
 I18n.enforce_available_locales = true
 
 require 'rspec/support/spec'
+require 'rspec/core/sandbox'
 require 'rspec/rails'
 require 'ammeter/init'
 
@@ -59,10 +60,16 @@ def self.run_all(reporter = nil)
   config.warnings = true
   config.raise_on_warning = true
 
+  # Execute a provided block with RSpec global objects (configuration,
+  # world, current example) reset. This is used to test specs with RSpec.
   config.around(:example) do |example|
-    real_world = RSpec.world
-    RSpec.instance_variable_set(:@world, RSpec::Core::World.new)
+    RSpec::Core::Sandbox.sandboxed do |sandbox_config|
+      # If there is an example-within-an-example, we want to make sure the inner
+      # example does not get a reference to the outer example (the real spec) if
+      # it calls something like `pending`.
+      sandbox_config.before(:context) { RSpec.current_example = nil }
+      RSpec::Rails.initialize_configuration(sandbox_config)
       example.run
-    RSpec.instance_variable_set(:@world, real_world)
+    end
   end
 end

spec/support/generators.rb

@@ -17,6 +17,7 @@ def setup_default_destination
 
         def self.included(klass)
           klass.extend(Macros)
+          klass.include(RSpec::Rails::FeatureCheck)
         end
 
         shared_examples_for 'a model generator with fixtures' do |name, class_name|

spec/support/shared_examples.rb

@@ -27,10 +27,6 @@ def define_group_in(path, group_definition)
     end
   end
 
-  around(:example) do |ex|
-    with_isolated_config(&ex)
-  end
-
   it "adds does not add `:type` metadata on inclusion" do
     mixin = self.mixin
     group = RSpec.describe { include mixin }