How do you mock out private properties with OCMock for iOS?

Question

I have a private property that is declared in the .m file of my class to be tested, let's call it ClassUnderTest. ClassUnderTest instantiates an instance of ClassToBeMocked. How do I use OCMock to mock out an instance of the ClassToBeMocked and assign it to the ClassUnderTest?

Answer 1

Re-declare the property in your test class. You can do the same for private methods. In ClassUnderTestTest.m:

@interface ClassUnderTest ()

@property(retain)ClassToBeMocked *instanceToBeMocked;

-(void)somePrivateMethod;

@end

Answer 2

Does the following work?

id classUnderTest = ... // get from somewhere
id mock = [OCMockObject mockForClass:[ClassToBeMocked class]];
[classUnderTest setValue:mock forKey:@"nameOfThatPrivateProperty"];

Not totally sure whether you can set private properties like this. I think it depends on what kind of property it is.