Verifying a delegate was called with Moq

Question

i got a class that gets by argument a delegate. This class invokes that delegate, and i want to unit test it with Moq. how do i verify that this method was called ?

exam

Answer 1

You can do something like that:

 public interface IWithFOOMethod
 {
     void FooAlikeMethod(int number);
 }

 Mock<IWithFOOMethod> myMock = new Mock<IWithFOOMethod>();

 A a = new A(myMock.Object.FooAlikeMethod);

 myMock.Verify(call => call.Foo(It.IsAny<int>()), Times.Once())

Answer 2

What about using an anonymous function? It can act like an inline mock here, you don't need a mocking framework.

bool isDelegateCalled = false;
var a = new A(a => { isDelegateCalled = true});

//do something
Assert.True(isDelegateCalled);

Answer 3

As of this commit Moq now supports the mocking of delegates, for your situation you would do it like so:

var fooMock = new Mock<Foo>();
var a = new A(fooMock.Object);

Then you can verify the delegate was invoked:

fooMock.Verify(f => f(5), Times.Once);

Or:

fooMock.Verify(f => f(It.IsAny<int>()), Times.Once);