VERIFY, DEVELOP: Improve unit test coverage (Optional, 10+ hours, repeatable)

Find an aspect of Wordplay for which we have low (or no) test coverage. (This is a risk for the project: we want to ensure that Wordplay works and that future changes don't break things!) Open a new issue to represent the test coverage work, write the tests, fix any bugs that arise in collaboration with the community, and submit a pull request to include the tests in the main project.

If you're a developer working on a bug fix or feature, you should also write unit tests to verify the behavior that you're fixing or implementing.

When you're done, submit a link to the accepted pull request.

You can submit this multiple times and get credit for each. If you submit multiple, include all issues for which you're requesting credit, not just the latest.