Shouldn't this just go in `test_requirements.txt`? If you're having trouble because you have a jinja import in an `__init__.py`, you could either move the helper code to a `tests.docx_builder.py` module or do something like: 

```
try:
    import Jinja2
except ImportError:
    Jinja2 = None
```

I'd say moving the helpers to a different module would probably be cleaner, since you would get an obvious error message when someone tried to run the tests without jinja.