def METHOD_NAME(self):
    dsrc = XYDataSource(np.zeros((self.n, 2), dtype=int),
                        none_for_empty=True)
    expected = None
    actual = dsrc.peek()
    assert actual == expected
    actual = dsrc.peek_rear()
    assert actual == expected
    actual = dsrc.pop()
    assert actual == expected
    actual = dsrc.pop_rear()
    assert actual == expected