test_utils.py

class InstanceOf:
    """Wrapper to compare only type, not whole instance.
    
    Example usage:
    
        def test_ok(m_ted):
            ...
            m_ted.assert_called_once_with(InstanceOf(NotificationRequest))
    """

    def __init__(self, class_):
        self.class_ = class_

    def __eq__(self, other):
        return isinstance(other, self.class_)