OCMock: return the same value as get by parameter

I have faced with a bit specific issue while writing unit tests with the OCMock framework.

Let's say I have some method with one parameter. What I need is to stub that method and get the same value back. The value is calculated, so I can't just return some predefined value via the usual stub.

Pseudo declaration of that method (objc):

- (id)doSomething:(id)value;

You can use OCMock's Method Swizzling capabilities:

@implementation OCmockPlaygroundTests

- (void)testStub{

    TestClass * mockObject = OCMPartialMock([TestClass new]);

    OCMStub([mockObject doSomethingWith:OCMOCK_ANY]).andCall(self, @selector(doSomethingWith:));
    NSString * testInput = @"TEST_INPUT";
    NSString * result = [mockObject doSomethingWith:testInput];
    XCTAssertTrue([testInput isEqualToString:result]);
}

- (NSString *)doSomethingWith:(NSString *)input{
    return input;
}

@end

Instead of the doSomethingWith: method of the TestClass OCMock will instead call the implementation defined in the test case which only returns the input.