How to check private members in objective C unit tests?

Considering this class :

@interface SampleClass : NSObject {
    NSMutableArray *_childs;
}

- (void)addChild:(ChildClass *)child;
- (void)removeChild:(ChildClass *)child;

@end

How can i t开发者_JS百科est when i add a child if the _childs array contains one object without adding a property to access it (because i don't want allow client code to access the _childs array) ?

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Create a @property for it in the class extension and use the property for all accesses, that way you are testing and using the same code.

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I'm not sure I correctly understand your question, I parse it as: While implementing addChild:, how do I prevent to insert objects a second time into _childs ?

There are two ways: if the order of your elements doesn't matter then you should simply use a NSMutableSet instead of an NSMutableArray. In this case the set takes care of everything:

- (void)addChild:(ChildClass *)child
{
    [_childs addObject:child];
}

If order is important, stick with the NSMutableArray and do it like this:

- (void)addChild:(ChildClass *)child
{
    if ([_childs containsObject:child]) return;

    [_childs addObject:child];
}

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Just make a -(int)childCount method that returns the count of the array.