def test_layers_view():
    X = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    L = np.array([[10, 11, 12], [13, 14, 15], [16, 17, 18]])
    real_adata = ad.AnnData(X)
    real_adata.layers["L"] = L
    view_adata = real_adata[1:, 1:]
    real_hash = joblib.hash(real_adata)
    view_hash = joblib.hash(view_adata)

    assert view_adata.is_view

    with pytest.raises(ValueError):
        view_adata.layers["L2"] = L + 2

    assert view_adata.is_view  # Failing to set layer item makes adata not view
    assert real_hash == joblib.hash(real_adata)
    assert view_hash == joblib.hash(view_adata)

    view_adata.layers["L2"] = L[1:, 1:] + 2

    assert not view_adata.is_view
    assert real_hash == joblib.hash(real_adata)
    assert view_hash != joblib.hash(view_adata)
def select_backend(self, backend_id=None):
        """
        Selects the backend corresponding to backend_id.
        If backend_id is none, refreshes the current configuration panel.

        @param backend_id: the id of the backend to select
        """
        selection = self.get_selection()
        if backend_id in self.backendid_to_iter:
            backend_iter = self.backendid_to_iter[backend_id]
            if selection:
                selection.select_iter(backend_iter)
        else:
            if self._get_selected_path():
                # We just reselect the currently selected entry
                self.on_select_row()
            else:
                # If nothing is selected, we select the first entry
                if selection:
                    selection.select_path("0")
        self.dialog.on_backend_selected(self.get_selected_backend_id())