RSpec: Expecting a message multiple times but with differing parameters

Question

I currently have some expectations set up on a mock with consecutive calls:

The spec:

@my_mock = mock("a_mock")
@options1 = {:some => "option"}
@options2 = {:some_other => "option"}
@first_param = mock("first_param")

@my_mock.should_receive(:a_message).with(@first_param, @options1)
@my_mock.should_receive(:a_message).with(@first_param, @options2)

However, i get the following:

Mock "a_mock" received :a_message with unexpected arguments
  expected: (#<Spec::Mocks::Mock:0x81b8ca3c @name="first_param"{:some => "option"})
   got: (#<Spec::Mocks::Mock:0x81b8ca3c @name="first_param">, {:some_other => "option"})

When I debug this, the first expectation IS getting called. Do I have to specify anything else before I can expect consecutive calls with the same message but differing parameters?

Answer 1

Try creating your mock as a null object to ignore extra method calls. Each of your expectations will still have to be met, but they won't step on each other.

@my_mock = mock("a_mock").as_null_object

This follows the Null Object pattern, in which any extraneous messages are just ignored. It is useful with mocks when you want to make sure a method gets called with certain parameters, but you don't care if it is called with other parameters or if any other methods get called.