Mock a method of the subject under test in Moq?

c#, mocking, moq

Solution

It is, with a catch! You have to make sure method `B` is virtual and can be overriden.

Then, set the mock to call the base methods whenever a setup is not provided. Then you setup `B`, but don't setup `A`. Because `A` was not setup, the actual implementation will be called.

var myClassMock = new Mock<MyClass>();
myClassMock.Setup(x => x.B()); //mock B

myClassMock.CallBase = true;

MyClass obj = myClassMock.Object;
obj.A(); // will call the actual implementation
obj.B(); // will call the mock implementation

Behinds the scenes, Moq will dynamically create a class that extends `MyClass` and overrides `B`.

Problem

I want to test method A of my class, but without calling the actual method B which is normally called by A. That's because B has a lot of external interactions I don't want to test for now. I could create mocks for all the services called by B, but that's quite some work. I'd rather just mock B and make it return sample data. Is that possible to do with Moq framework?

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