def METHOD_NAME(self):
    """ Verify compare_signature errors if string key does not match. """
    provider = CreditProviderFactory(
        provider_id='asu',
        active=False,
    )
    # Create a serializer that has a signature which was created with a key
    # that we do not have in our system.
    sig = signature.signature({}, 'iamthewrongkey')
    serializer = serializers.CreditProviderCallbackSerializer(
        data={'signature': sig}
    )
    with pytest.raises(PermissionDenied):
        # The first arg here is key we have (that doesn't match the sig)
        serializer._compare_signatures('abcd1234', provider.provider_id)  # lint-amnesty, pylint: disable=protected-access