Testing

[sviperll]

I still have no idea how to create proper tests for annotation processor. adt4j-examples project becomes unwieldy. We need code with compile-time errors to proper test adt4j.

[talios]

I suggest maybe looking at doing some invoker based IT tests possibly? I'll try add at least one on the weekend and submit a PR.

[jbgi]

maybe this project can help: https://github.com/google/compile-testing