What is the difference between a mock and a fake

I could use a stub like so :. This is what stubs are great at. So where would we use Mocks? So all we are doing is checking if a shop is open or closed. If we used fakes here, we would need to add some dummy method to be able to say whether a shop should be open or closed. Maybe something like this :. Eh, not great in my eyes. We are adding new methods just to be able to control whether a shop is open or closed for the test.

Maybe even something like this :. This works with a predefined list of ids, and whether a shop will be open or closed. So how would you solve this using mocks? You would write something like this right there in your test I am using the Moq library for this! I feel I have to atleast throw my 2 cents in here on when to use each one. For now, hopefully you understand a little better what each of these test doubles are used for and maybe a little more of a nudge on when to use each one.

We can create our own mock in Swift like this:. This looks a lot like our stub, but it has a little extra functionality. It tracks whether the fetch method was called with the fetchWasCalled property. When we call the title method on our view model, we expect the view model to call fetch on our BlogClientMock.

This gives us a little more confidence in our view model — we know that the method was called as expected. If we wanted to be even more sure that things are working correctly, we could also make an assertion about the title like we did in our stub test. You can take mocks even further — if you have a method with parameters, for example, your mock can track the values you passed as parameters to the method. This allows you to verify not only that the method was called , but that it was called with the correct parameter values.

And furthermore, you can track the number of times the method was called with a property like fetchCallCount , for example and verify that fetch was called the correct number of times. In general, I prefer to stub. Unit testing for iOS can be lonely — most iOS developers don't seem to be doing it. GetUserRole "admin". Returns "administrator" ; mockedUserStore. GetUserRole "user1". Returns "contributor" ; mockedUserStore.

GetUserRole "user2". Returns "basic" ; Which one shall I use? I would recommend starting with the lightest implementation first.

Try to avoid mocks if the same scenarios can be reproduced with simple stubs and fakes. Use Stub to represent database objects and use Fake and Spy to mimic the behavior of business interfaces or services like retry, logging, etc.

Mocks sometimes make test cases difficult to read and difficult to understand. Improper use of Mock may impact test strategy in a negative way. View All. Mangesh Kulkarni Updated date Jul 28,