anchor.diff:  
   [source,groovy]
   ----
  -def subscriber = Mock(Subscriber) {
  +Subscriber subscriber = Mock {
      1 * receive("hello")
      1 * receive("goodbye")
   }
  
positive.code: 
  [source,groovy]
  ----
  def subscriber = Stub(Subscriber)
  ----
  
  Whereas a mock can be used both for stubbing and mocking, a stub can only be used for stubbing.
  
negative.code: 
  [source,groovy]
  ----
  Subscriber subscriber = GroovyMock()
  
  1 * subscriber.someDynamicMethod("hello")
  ----
  