Rhino Mocks，设置存根属性后如何执行操作

Question

I have a simple requirement, but I seem to be struggling.

I have created a stub that mocks an interface that includes a Property :

public interface IMockIRuleRuningViewModel : IRuleRunningViewModel
{
    int Id { get; set; }
}

And the mock is :

var mock = MockRepository.GenerateStub<IMockIRuleRuningViewModel>();

Now I want to mock an action that I would have put in a setter for this Property , and here is my attempt :

mock.Stub(x => x.Id).WhenCalled(
    o =>
        {
            var engine = new RulesEngine(mock);
            mock.ProcessRuleEngineResults(engine.RunRule("Id"));
        });

But I keep getting this Exception :

You are trying to set an expectation on a property that was defined to use PropertyBehavior. Instead of writing code such as this: mockObject.Stub(x => x.SomeProperty).Return(42); You can use the property directly to achieve the same result: mockObject.SomeProperty = 42;

Answer 1

The following works for me:

HttpResponseBase response = MockRepository.GenerateMock<HttpResponseBase>();

// stub the getter
response.Stub(r => r.StatusCode).Return((int)HttpStatusCode.OK);

// Stub the setter
response.Stub(r => r.StatusCode = Arg<int>.Is.Anything).WhenCalled( o =>
  {
    Console.WriteLine("called");
  });

Since what I'm actually trying to do is model the case where you can get but not set the status code (because headers have already been sent), I don't do WhenCalled() , I do this:

 response.Stub(r => r.StatusCode = Arg<int>.Is.Anything)
   .Throw(new HttpException("Server cannot set status after HTTP headers have been sent"));

You have to use MockRepository.GenerateMock not MockRepository.GenerateStub . I don't know why.

Answer 2

If you want to verify the behavior of the SUT (system under test), you should use a mock with the appropriate expectation, and verify that. If you want just to pass a value that may need to act in a certain way, but isn't the focus of this test, you will use a stub (stub will not cause a test to fail).

I assume that you are testing RulesEngine in this test (because it is only real object I see). Here is a sample test, which verifies behavior of engine, when "Id" rule was executed:

// Arrange
var model = MockRepository.GenerateMock<IMockIRuleRuningViewModel>();
model.Expect(m => m.ProcessEngineResults(42));
RulesEngine engine = new RulesEngine(model);

// Act
engine.RunRule("Id");

// Assert
model.VerifyAllExpectations();