def test_serialization_error_message_for_incorrect_datetime_string():
    """Test if error message is using original error message
    from datetime lib, and is properly formatted.
    """
    result = execute_mutation("2021-13-01T09:00:00")
    assert result.errors
    assert result.errors[0].message == (
        "Variable '$value' got invalid value '2021-13-01T09:00:00'; Value cannot "
        'represent a DateTime: "2021-13-01T09:00:00". month must be in 1..12'
    )
Test if error message is using original error message
    from datetime lib, and is properly formatted.
    
tests/schema/types/test_datetime.py