def test_drop_obs_column():
    adata = ad.AnnData(np.array(X_list), obs=obs_dict, dtype="int32")

    subset = adata[:2]
    assert subset.is_view
    # returns a copy of obs
    assert subset.obs.drop(columns=["oanno1"]).columns.tolist() == ["oanno2", "oanno3"]
    assert subset.is_view
    # would modify obs, so it should actualize subset and not modify adata
    subset.obs.drop(columns=["oanno1"], inplace=True)
    assert not subset.is_view
    assert subset.obs.columns.tolist() == ["oanno2", "oanno3"]

    assert adata.obs.columns.tolist() == ["oanno1", "oanno2", "oanno3"]
def test_emtpy(self):
        # I had problems with these
        #
        # Although these are patological cases: Empty Structures!
        class X(Structure):
            _fields_ = []

        class Y(Union):
            _fields_ = []

        # Is this really the correct alignment, or should it be 0?
        self.assertTrue(alignment(X) == alignment(Y) == 1)
        self.assertTrue(sizeof(X) == sizeof(Y) == 0)

        class XX(Structure):
            _fields_ = [("a", X),
                        ("b", X)]

        self.assertEqual(alignment(XX), 1)
        self.assertEqual(sizeof(XX), 0)