def test_model_one_undo_redo(self):
model = CanvasModel(self.eb)
model.commit([ Insert(R(1, 1, 1, 1)) ])
assert model._elems == [ R(1, 1, 1, 1) ]
assert model._changelog == [ [ Insert(R(1, 1, 1, 1)) ] ]
assert model._redolog == []
model.undo()
assert model._elems == []
assert model._changelog == []
assert model._redolog == [ [ Insert(R(1, 1, 1, 1)) ] ]
model.redo()
assert model._elems == [ R(1, 1, 1, 1) ]
assert model._changelog == [ [ Insert(R(1, 1, 1, 1)) ] ]
assert model._redolog == []
