Fix RSpec 4 shared context inclusion

Starting from RSpec 4, the implicit shared context inclusion, when a
shared context would have been included to an example if the example has
matching metadata, is not the case anymore.

See:
 - rspec/rspec-core#2834
 - rspec/rspec-core#2832
 - rspec/rspec-core#2878

spec/spec_helper.rb

@@ -38,6 +38,10 @@ module SpecHelper
   config.raise_on_warning = true
 
   config.include(ExpectOffense)
+
+  config.include_context 'with default RSpec/Language config', :config
+  config.include_context 'config', :config
+  config.include_context 'smoke test', type: :cop_spec
 end
 
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))