I didn't write tests for the `FileExamples` class because the following options were not ideal:

-  I could mock the `File` class and fake a directory structure, but I couldn't determine whether SBT has a dependency on a mock framework (such as Mockito). If you're okay with adding a mocking framework to SBT I can go ahead with this. (Btw, I suggest using Mockito. I have some experience using Mockito in ScalaTest, and it's something I would recommend. Having mocks would also help in the other tests I wrote.)

- I could subclass `File` and create fake files and with a fake directory structure. This could work, but I'd have to create boolean flags or counters to verify that certain paths have not been traversed (when limiting the number of examples).

- I could simply use SBT's own directory structure and files in the test. However, I would recommend strongly against this for a number of reasons: tests now depend on external state that has nothing to do with the tests, hidden dependency, no way to verify whether a directory has been traversed or not (unlike the two approaches above).

What to do?