Adding Swift files to test target not fixing unit tests
After much headache and putting this on the back burner, I found that the main problem was when adding files to the test target membership, the Objective-C classes would still complain. I figured it was an old compatibility issue with the new way Swift does unit tests, but the solution was my test target didn't know there was a bridging header. Thus, I added a reference to it in my test target's build settings, like so:
It seems simple and obvious now, but the errors were unhelpful. No other solutions I saw for Swift unit tests suggested this could be an issue, but now I know.
For unit tests to work in Swift, the test target must know everything the app target knows, so add a reference to your bridging header in your test target too (if applicable).