Objective C & OC Mock - Mocking a class method?

Question

I need to be able to determine whether a class method was called or not. How can I do this with OCMock?

Answer 1

Starting with OCMock release 2.1 this is supported out of the box. You can now stub class methods in the same way as you stub instance methods.

Answer 2

One approach is to wrap the class method in a method on your own class. So let's say your class has to call [SomeOtherClass classMethod:someString]. You could create a method invokeClassMethod: on your class like this:

-(NSString *)invokeClassMethod:(NSString *)someString {
    return [SomeOtherClass classMethod:someString];
}

Then in your test, you create a partial mock and expect invokeClassMethod:

-(void)testSomething {
    id partialMock = [OCMockObject partialMockForObject:actual];
    [[[partialMock expect] andReturn:@"foo"] invokeClassMethod:@"bar"];

    [actual doSomething:@"bar"];

    [partialMock verify];
}

If you want to verify that invokeClassMethod isn't called, you can throw an exception:

-(void)testSomethingElse {
    id partialMock = [OCMockObject partialMockForObject:actual];
    [[[partialMock stub] andThrow:[NSException exceptionWithName:@"foo" reason:@"Should not have called invokeClassMethod:" userInfo:nil] invokeClassMethod:OCMOCK_ANY];

    [actual doSomething:@"bar"];
}

The excpetion will cause the test to fail if invokeClassMethod is called.