class Rspec::Core::ExampleGroup

def self.subclass(base_name, &body) # :nodoc:
  @_subclass_count ||= 0
  @_subclass_count += 1
  klass = Class.new(self)
  class_name = "#{base_name}_#{@_subclass_count}"
  const_set(class_name, klass)
  klass.instance_eval(&body)
  klass
end