Function test_to_pybuffer_contiguity

tests/test_buffers.py:345–401

(type)

@pytest.mark.parametrize("type", ["pybind11", "numpy"])
def test_to_pybuffer_contiguity(type):
    def check_strides(mat):
        # The full block is memset to 0, so fill it with non-zero in real spots.
        expected = np.arange(1, 5 * 4 + 1).reshape((5, 4))
        for i in range(5):
            for j in range(4):
                mat[i, j] = expected[i, j]
        # If all strides are correct, the exposed buffer should match the input.
        np.testing.assert_array_equal(np.array(mat), expected)

    if type == "pybind11":
        cmat = m.Matrix(5, 4)  # C contiguous.
        fmat = m.FortranMatrix(5, 4)  # Fortran contiguous.
        dmat = m.DiscontiguousMatrix(5, 4, 2, 3)  # Not contiguous.
        expected_exception = BufferError
    elif type == "numpy":
        cmat = np.empty((5, 4), dtype=np.float32)  # C contiguous.
        fmat = np.empty((5, 4), dtype=np.float32, order="F")  # Fortran contiguous.
        dmat = np.empty((5 * 2, 4 * 3), dtype=np.float32)[::2, ::3]  # Not contiguous.
        # NumPy incorrectly raises ValueError; when the minimum NumPy requirement is
        # above the version that fixes https://github.com/numpy/numpy/issues/3634 then
        # BufferError can be used everywhere.
        expected_exception = (BufferError, ValueError)
    else:
        raise ValueError(f"Unknown parametrization {type}")

    check_strides(cmat)
    # Should work in C-contiguous mode, but not Fortran order.
    m.get_py_buffer(cmat, m.PyBUF_C_CONTIGUOUS)
    m.get_py_buffer(cmat, m.PyBUF_ANY_CONTIGUOUS)
    with pytest.raises(expected_exception):
        m.get_py_buffer(cmat, m.PyBUF_F_CONTIGUOUS)

    check_strides(fmat)
    # These flags imply C-contiguity, so won't work.
    with pytest.raises(expected_exception):
        m.get_py_buffer(fmat, m.PyBUF_SIMPLE)
    with pytest.raises(expected_exception):
        m.get_py_buffer(fmat, m.PyBUF_ND)
    # Should work in Fortran-contiguous mode, but not C order.
    with pytest.raises(expected_exception):
        m.get_py_buffer(fmat, m.PyBUF_C_CONTIGUOUS)
    m.get_py_buffer(fmat, m.PyBUF_ANY_CONTIGUOUS)
    m.get_py_buffer(fmat, m.PyBUF_F_CONTIGUOUS)

    check_strides(dmat)
    # Should never work.
    with pytest.raises(expected_exception):
        m.get_py_buffer(dmat, m.PyBUF_SIMPLE)
    with pytest.raises(expected_exception):
        m.get_py_buffer(dmat, m.PyBUF_ND)
    with pytest.raises(expected_exception):
        m.get_py_buffer(dmat, m.PyBUF_C_CONTIGUOUS)
    with pytest.raises(expected_exception):
        m.get_py_buffer(dmat, m.PyBUF_ANY_CONTIGUOUS)
    with pytest.raises(expected_exception):
        m.get_py_buffer(dmat, m.PyBUF_F_CONTIGUOUS)