Refactor tests

[jakobnissen]

The tests are fairly thorough, but I think they would be better if they were factored out into more testsets. It would make it easier to add new unit tests. I've though this every time when looking at the tests, so just making the issue here so I don't forget.

When (if) the refactoring ever happens, this would also be a good chance to push the coverage a little higher.