Google Code-in

The Wikilabels AI service, https://github.com/wiki-ai/wikilabels, uses flask, however, there're no tests so far. Your task is to introduce pytest-flask into the project, https://github.com/pytest-dev/pytest-flask, and create at least one test, which passes in our CI infrastructure.

If you've questions, feel free to contact Ladsgroup in IRC (#wikimedia-dev) or in the phabricator task (see the external url).