I created a new Class Library (UWP) project set it up for unit tests (see https://stackoverflow.com/a/34175226/3609052 for how I set it up).
Everything builds find and the tests show up, but when I right click and run the tests it builds and doesn't do anything. They don't run.
I found my problem. The unit tests require a runner, which means I must have a Unit Test Project. I found this in the output.