Question

I have a Rails controller action to test. In that action, a method User.can? is invoked several times with different parameters. In one of the test case for it, I want to make sure that User.can?(‘withdraw’) is invoked. But I don’t care about invocations of User.can? with other parameters.

def action_to_be_tested
  ...
  @user.can?('withdraw')
  ...
  @user.can?('deposit')
  ...
end

I tried below in the test:

User.any_instance.expects(:can?).with('withdraw').at_least_once.returns(true)

But the test failed with message indicating unexpected invocation of User.can?(‘deposit’).
If I add another expectation with parameter ‘deposit’, the test passed. But I am wondering if there are any ways such that I could just focus on the invocation with ‘withdraw’ parameter (because other invocations are irrelevant to this test case).

Answer 1

I just found a workaround, by stubbing out invocations with irrelevant parameters:

User.any_instance.expects(:can?).with('withdraw').at_least_once.returns(true)
User.any_instance.stubs(:can?).with(Not(equals('withdraw')))

http://mocha.rubyforge.org/classes/Mocha/ParameterMatchers.html#M000023