public void GetAllUserBets_Should_BeCalledOnce_WhenTheCorrectRepositoryIsPassed() { var betRepositoryMock = MockRepository.GenerateMock <IBetRepository>(); //Arrange betRepositoryMock.Expect(dao => dao.GetAllUserBets(Arg <string> .Is.Anything)).Return(Arg <IEnumerable <Bet> > .Is.Anything).Repeat.Once();; var betService = new BetService(betRepositoryMock); //Act betService.GetAllUserBets("1"); //Assert betRepositoryMock.VerifyAllExpectations(); }