Rhino Mocks - mocking a method whose return value changes (even when passed the same parameter) with multiple calls

Question

I'm looking to find out how I can mock a method that returns a different value the second time it is called to the first time. For example, something like this:

public interface IApplicationLifetime {     int SecondsSinceStarted {get;} }  [Test] public void Expected_mock_behaviour() {     IApplicationLifetime mock = MockRepository.GenerateMock<IApplicationLifetime>();      mock.Expect(m=>m.SecondsSinceStarted).Return(1).Repeat.Once();     mock.Expect(m=>m.SecondsSinceStarted).Return(2).Repeat.Once();      Assert.AreEqual(1, mock.SecondsSinceStarted);     Assert.AreEqual(2, mock.SecondsSinceStarted); } 

Is there anything that makes this possible? Besides implementing a sub for the getter that implements a state machine?

Answer 1

You can intercept return values with the .WhenCalled method. Note that you still need to provide a value via the .Return method, however Rhino will simply ignore it if ReturnValue is altered from the method invocation:

int invocationsCounter = 1; const int IgnoredReturnValue = 10; mock.Expect(m => m.SecondsSinceLifetime)     .WhenCalled(mi => mi.ReturnValue = invocationsCounter++)     .Return(IgnoredReturnValue);  Assert.That(mock.SecondsSinceLifetime, Is.EqualTo(1)); Assert.That(mock.SecondsSinceLifetime, Is.EqualTo(2)); 

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Digging around a bit more, it seems that .Repeat.Once() does indeed work in this case and can be used to achieve the same result:

mock.Expect(m => m.SecondsSinceStarted).Return(1).Repeat.Once(); mock.Expect(m => m.SecondsSinceStarted).Return(2).Repeat.Once(); mock.Expect(m => m.SecondsSinceStarted).Return(3).Repeat.Once(); 

Will return 1, 2, 3 on consecutive calls.