Any reading or advice I've been given on Unit Testing has always suggested a distinct difference between the definition of a Mock and a Stub. My current understanding of these definitions are as follows
Mock: A fake which will be used in your test to make a final assertion
Stub: A fake which will be used in your test to isolate a dependency but not be asserted
However, Moq appears to only allow the creation of Mocks. The Stub namespace in the framework appears to be depreciated with recommendations to use Mock.SetupXXX.
Am I missing something in my understanding of this? Or is there a general understanding that a mock object can infact be used as nothing more that a stub?
Perhaps I am being pedantic, it's just that I have always found language in programming to be very strict and prefer to get my usage of it correct, especially when other developers might be taking over a project.
imho its just that its kind of a silly discussion.
What matters is that you use the mocks/stubs to assert what you need to in the test, and don't assert what you don't.
Martin Fowler wrote a good article, Mocks Aren't Stubs, which I think makes the distinction clear.
Mocks are used for behavior verification, while stubs supply fake data and normally participate in state verification.
Indeed, Moq can create true stubs. From the Moq Quick Start page:
IMHO, the distinctions between flavors of fakes is best thought of as a distinction between functions of those fakes rather than types of fakes, as a fake may take on multiple roles at once (e.g. can be a true mock and a saboteur all at once), and as no such distinction is necessary for using a mock framework. (I should blog about this!)
According to the Moq project site, Moq provides:
The lack of distinction between mocks, stubs, and such is a deliberate design decision; A design decision which I, for one, prefer. If I need a true mock, I call
Verify()
on it. If not, there's noVerify()
. I like the simplicity, and I haven't found myself missing the distinction betweenmock
andstub
.