Const behavior test with googletest

I am using google test to write some unit tests for a container class with iterators. I would like to create a test that ensures mine is const_iterator

correct const

: namely, that I cannot assign it

MyContainer<MyType>::const_iterator cItr = MyContainerInstance.cbegin();
*cItr = MyType();    // this should fail.


Obviously this won't compile (IFF is correctly coded), but is there a way to use google test to leave some kind of check like this in the unit test? Or in some way without a Google test that doesn't require another library to be integrated?


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1 answer

This way it can be determined if an iterator is a constant iterator, but this is more complicated than I originally thought.

Keep in mind that you don't need an actual instance of your constant iterator, since all you do is type checking:

// Include <type_traits> somewhere

typedef MyContainer<MyType>::const_iterator it;
typedef std::iterator_traits<it>::pointer ptr;
typedef std::remove_pointer<ptr>::type iterator_type;
std::cout << std::boolalpha << std::is_const<iterator_type>::value;
// This'll print a 0 or 1 indicating if your iterator is const or not.


And then you can check in the usual way in gtest with:



Free advice: I think it's best to let your compiler check this for you by simply writing a test that won't compile if it breaks const correctness.

You can check this with std::vector


typedef std::vector<int>::const_iterator c_it;
typedef std::iterator_traits<c_it>::pointer c_ptr;
typedef std::remove_pointer<c_ptr>::type c_iterator_type;

typedef std::vector<int>::iterator it;
typedef std::iterator_traits<it>::pointer ptr;
typedef std::remove_pointer<ptr>::type iterator_type;


This should compile and run.



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