def test_add(self):
        data = core.Data()
        assert not self.layer_present(data)
        self.add_layer(data)
        assert self.layer_present(data)
Test that a layer exists in widget once added
dataset/ETHPy150Open glue-viz/glue/glue/app/qt/tests/test_layer_tree_widget.py/TestLayerTree.test_add