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 on_backend_added(self, sender, backend_id):
        """
        Signal callback executed when a new backend is loaded

        @param sender: not used, only here to let this function be used as a
                       callback
        @param backend_id: the id of the backend to add
        """
        # Add
        backend = self.req.get_backend(backend_id)
        if not backend:
            return
        self.add_backend(backend)
        self.refresh()
        # Select
        self.select_backend(backend_id)
        # Update it's enabled state
        self.on_backend_state_changed(None, backend.get_id())