'Test that building a URL caches it'

def test_build_url_caches_built_urls(self):

    s = self.build_session()
    url = s.build_url('gists', '123456', 'history')
    url_parts = ('https://api.github.com', 'gists', '123456', 'history')
    assert (url_parts in session.__url_cache__)
    assert (url in session.__url_cache__.values())
