'Test that a 3x3 unit kernel returns the same array (except when
boundary is None).'

@pytest.mark.parametrize(u'boundary', BOUNDARY_OPTIONS)
def test_unity_3x3(self, boundary):

    x = np.array([[1.0, 2.0, 3.0], [4.0, 5.0, 6.0], [7.0, 8.0, 9.0]], dtype=u'>f8')
    y = np.array([[0.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 0.0]], dtype=u'>f8')
    z = convolve(x, y, boundary=boundary)
    if (boundary is None):
        assert np.all((z == np.array([[0.0, 0.0, 0.0], [0.0, 5.0, 0.0], [0.0, 0.0, 0.0]], dtype=u'>f8')))
    else:
        assert np.all((z == x))
