Function test_binary_operator_delegation

dask/array/tests/test_array_core.py:1233–1275

(mocker)

def test_binary_operator_delegation(mocker):
    # Binary operator delegation in Dask should follow Numpy's:
    # https://numpy.org/neps/nep-0013-ufunc-overrides.html#behavior-in-combination-with-python-s-binary-operations

    x = from_array([1, 2, 3])

    # Mock various types of `other` objects
    ufunc_none = mocker.Mock()
    ufunc_none.__array_ufunc__ = None
    ufunc_none.__radd__ = mocker.Mock()

    ufunc_high_priority = mocker.Mock()
    ufunc_high_priority.__array_priority__ = x.__array_priority__ + 1
    ufunc_high_priority.__radd__ = mocker.Mock()

    ufunc_low_priority = mocker.Mock()
    ufunc_low_priority.__array_priority__ = x.__array_priority__ - 1
    ufunc_low_priority.__radd__ = mocker.Mock()

    ufunc_no_priority = mocker.Mock()
    ufunc_no_priority.__radd__ = mocker.Mock()

    # If `other.__array_ufunc__ is None`, delegates back to Python
    # and therefore call reflected operator on `other`
    x + ufunc_none
    ufunc_none.__radd__.assert_called_once()

    # If the `__array_ufunc__` attribute is absent on other and
    # `other.__array_priority__ > self.__array_priority__`, also delegates back
    # to Python and therefore call reflected operator on `other`
    x + ufunc_high_priority
    ufunc_high_priority.__radd__.assert_called_once()

    # If `other.__array_priority__ <= self.__array_priority__`, does not
    # delegate (here it raises an error)
    with pytest.raises(TypeError):
        x + ufunc_low_priority
    ufunc_low_priority.__radd__.assert_not_called()

    # If `other.__array_priority__` is absent, does not delegate (raises)
    with pytest.raises(TypeError):
        x + ufunc_no_priority
    ufunc_no_priority.__radd__.assert_not_called()


@pytest.mark.filterwarnings("ignore:overflow encountered in cast")  # numpy >=2.0