It `setUp` fails part way `tearDown` won't get called which will then make subsequent tests fail in confusing ways possibly. I think the `mock.patch` decorator actually makes sense here -- then we can do:

```python
@patch('go.routing.views._get_routing_table')
def test_foo(self, mock_routing):
    mock_routing.return_value = self.make_routing_table()
    ...
```