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  • Feature proposal: unittest.mock.NAN

    From Kerrick Staley@21:1/5 to All on Wed Jan 24 12:11:25 2024
    I think we should define a unittest.mock.NAN constant that can be used with Mock.assert_called_with() to assert that an argument passed to a Mock was
    NaN. NaNs are special in that math.nan != math.nan, so you can't just do assert_called_with(math.nan). The naming is meant to parallel unittest.mock.ANY.

    Here is a reference implementation:

    class _EqNaN:
    def __eq__(self, other):
    return math.isnan(other)

    NAN = _EqNaN()

    The alternative is that users can just define this EqNaN class themselves
    as needed in test code. I encountered the need to test for a NaN argument
    today and was surprised to find that (as far as I can tell) there is no pre-built solution to this in unittest or pytest. It feels like it should
    be included in some standard library.

    - Kerrick

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  • From Barry Scott@21:1/5 to All on Wed Jan 24 21:08:12 2024
    Python ideas are discussed here these days: https://discuss.python.org/
    Suggest you raise this there in the Ideas category.

    Barry


    On 24 Jan 2024, at 17:11, Kerrick Staley via Python-list <python-list@python.org> wrote:

    I think we should define a unittest.mock.NAN constant that can be used with Mock.assert_called_with() to assert that an argument passed to a Mock was NaN. NaNs are special in that math.nan != math.nan, so you can't just do assert_called_with(math.nan). The naming is meant to parallel unittest.mock.ANY.

    Here is a reference implementation:

    class _EqNaN:
    def __eq__(self, other):
    return math.isnan(other)

    NAN = _EqNaN()

    The alternative is that users can just define this EqNaN class themselves
    as needed in test code. I encountered the need to test for a NaN argument today and was surprised to find that (as far as I can tell) there is no pre-built solution to this in unittest or pytest. It feels like it should
    be included in some standard library.

    - Kerrick
    --
    https://mail.python.org/mailman/listinfo/python-list


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  • From Stefan Ram@21:1/5 to Kerrick Staley on Wed Jan 24 20:34:01 2024
    Kerrick Staley <k@kerrickstaley.com> writes:
    NaNs are special in that math.nan != math.nan, so you can't just do
    assert_called_with(math.nan).

    class ProductionClass:
    ... def method(self):
    ... self.something( math.nan )
    ... def something( self, x ):
    ... pass
    ...
    real = ProductionClass()
    real.something = MagicMock()
    real.method()
    real.something.assert_called_once_with( math.nan )


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