Tests cookies.

def get_context_data(self, **kwargs):
        """Tests cookies.
        """
        self.request.session.set_test_cookie()
        if not self.request.session.test_cookie_worked():
            messages.add_message(
                self.request, messages.ERROR, "Please enable cookies.")
        self.request.session.delete_test_cookie()
        return super().get_context_data(**kwargs)