gistfile1.cs

    [TestFixture]
    public class WebServiceTest 
    {
        [Test]
        public void should_call_authentication_service()
        {
            service.MyMethod();
            Verify<IAuthenticationService>(a => a.Authenticate(username, password)).WasCalled();
        }
    }

    [TestFixture]
    public class AuthenticationServiceTest
    {
        [Test]
        [ExpectedException(typeof(UnauthorizedAccessException))]
        public void should_throw_when_user_not_found()
        {
            Mock<IUserRepository>().Expect(u => u.FindByUserName("i")).Returns(null);
            authenticationService.Authenticate("i", "notMyPassword");
        }

        [Test]
        [ExpectedException(typeof(UnauthorizedAccessException))]
        public void should_throw_when_invalid_password()
        {
            Mock<IUserRepository>().Expect(u => u.FindByUserName("i")).Returns(new User("i", "password"));
            authenticationService.Authenticate("i", "notMyPassword");
        }

        [Test]
        public void should_return_true_when_valid_password()
        {
            Mock<IUserRepository>().Expect(u => u.FindByUserName("i")).Returns(new User("i", "password"));
            authenticationService.Authenticate("i", "password").ShouldBeTrue();
        }
    }