I am learning OCMock for iOS testing. What's the difference between "class mock" and "partial mock", and when should you use one vs the other?
http://ocmock.org/features/
Class mocks
create objects that are pure mocks of a class instance.
Partial mocks
take an instance of a class an allow you to stub any of its methods.
Suppose I have these classes:
@interface Foo : NSObject
- (void)doX;
@end
@implementation
- (void)doX
{
NSLog(@"X");
}
@end
@interface Bar : NSObject
- (void)doA:(Foo *)foo;
- (void)doB;
@end
@implementation Bar
- (void)doA:(Foo *)foo
{
NSLog(@"A");
[foo doX];
[self doB];
}
- (void)doB
{
NSLog(@"B");
}
@end
I'm interested in testing Bar's doA:
method. I expect it to call doX
on a Foo
object, then to call its own doB
method. I would implement this using a class mock of a Foo and a partial mock of a Bar.
- (void)test_doA_shouldCall_doX_and_doB
{
id objectUnderTest = [OCMockObject partialMockForObject:[Bar new]];
id fooMock = [OCMockObject mockForClass:Foo.class];
[[fooMock expect] doX];
[[objectUnderTest expect] doB];
// Make the call
[objectUnderTest doA:fooMock];
[objectUnderTest verify];
[fooMock verify];
}
You see here that my partial mock allowed me to call the real method I wanted to test while mocking an internal call to another of its instance methods. Because I didn't need any of the real functionality of Foo, however, I used a class mock.
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