SFML/test/TestUtilities/WindowUtil.cpp

// Note: No need to increase compile time by including TestUtilities/Window.hpp
#include <SFML/Window/VideoMode.hpp>
#include <ostream>

namespace sf
{
    std::ostream& operator <<(std::ostream& os, const sf::VideoMode& videoMode)
    {
        os << videoMode.size.x << "x" << videoMode.size.y << "x" << videoMode.bitsPerPixel;
        return os;
    }
}