Asserting that a method is called exactly one time

Question

I want to assert that a method is called exactly one time. I'm using RhinoMocks 3.5.

Here's what I thought would work:

[Test] public void just_once() {     var key = "id_of_something";      var source = MockRepository.GenerateStub<ISomeDataSource>();     source.Expect(x => x.GetSomethingThatTakesALotOfResources(key))         .Return(new Something())         .Repeat.Once();      var client = new Client(soure);      // the first call I expect the client to use the source     client.GetMeMyThing(key);      // the second call the result should be cached     // and source is not used     client.GetMeMyThing(key); } 

I want this test to fail if the second invocation of GetMeMyThing() calls source.GetSomethingThatTakesALotOfResources().

Answer 1

Here's how I'd verify a method is called once.

[Test] public void just_once() {     // Arrange (Important to GenerateMock not GenerateStub)     var a = MockRepository.GenerateMock<ISomeDataSource>();     a.Expect(x => x.GetSomethingThatTakesALotOfResources()).Return(new Something()).Repeat.Once();      // Act     // First invocation should call GetSomethingThatTakesALotOfResources     a.GetMeMyThing();      // Second invocation should return cached result     a.GetMeMyThing();      // Assert     a.VerifyAllExpectations(); } 

Answer 2

I have been using the AssertWasCalled extension to get around this problem. This is the best I could find/come up with but it would be better if I didn't have to specify the call twice.

    [Test]     public void just_once()     {         var key = "id_of_something";          var source = MockRepository.GenerateStub<ISomeDataSource>();          // set a positive expectation         source.Expect(x => x.GetSomethingThatTakesALotOfResources(key))             .Return(new Something())             .Repeat.Once();          var client = new Client(soure);         client.GetMeMyThing(key);         client.GetMeMyThing(key);          source.AssertWasCalled(x => x.GetSomethingThatTakesALotOfResources(key),                                x => x.Repeat.Once());         source.VerifyAllExpectations();     }