OCMock stub class methods of the class that is being tested

Question

+(NSString *) classMethod:(id)someDataObject
{
    NSString *returnStr;

    //do something with someDataObject and set returnStr
    //...    

    returnStr = [NSString stringWithFormat:@"%@%@", returnStr,[self getCurrentTimestamp]];

    return returnStr;
}

+ (NSString *)getCurrentTimestamp
{
    NSNumber *t = [NSNumber numberWithLong:[[NSDate date] timeIntervalSince1970]];
    return [t stringValue];
}

I am struggling to write test case for the classMethod because when I run OCUnit test and pass OCMock object to classMethod the output will be always different as I add timestamp. What is the best approach to stub class method - getCurrentTimestamp? Is it actually possible to stub class methods of the class that is being tested?

I tried like this, but it is not working:

 id mock =  [OCMockObject mockForClass:[MyClass class]];
 [[[mock stub] andReturn:@1378468455] getCurrentTimestamp];

 NSString *str = [MyClass classMethod:someMockObject];

I notice your stub is returning an NSNumber and not and NSString -- not sure if that is the issue... — Ben Flynn

Ben Flynn Ben Flynn · Accepted Answer · 2013-09-06T15:22:42

This works fine for me:

+(NSString *) classMethod:(id)someDataObject
{
    NSString *returnStr = @"prefix-";
    returnStr = [NSString stringWithFormat:@"%@%@", returnStr,[self getCurrentTimestamp]];
    return returnStr;
}

+ (NSString *)getCurrentTimestamp
{
    NSNumber *t = [NSNumber numberWithLong:[[NSDate date] timeIntervalSince1970]];
    return [t stringValue];
}

- (void)testClass
{
    id mock =  [OCMockObject mockForClass:[Bar class]];
    [[[mock stub] andReturn:@"1378468455"] getCurrentTimestamp];   
    NSString *str = [Bar classMethod:nil];
    NSLog(@"Str: %@", str);
}

// Result: 
// Str: prefix-1378468455

Can you confirm your OCMock version, change the number to a string, and / or explain how it is not working for you?

OCMock stub class methods of the class that is being tested

2 Answers