While working on UIMA-6128, I at one point switched my local repo to master, made a new branch from this, and merged into that the v2 master, to pick up the 6128 change.
To my surprise, when I tried running a test build on uimaj-core (which had the changes), the test failed, running 2 test classes that were in the v2 version, but not in the v3 version. I went looking (via grep for file names or file contents of the particular test) in the checked out working directory, but found nothing. This wasn't an Eclipse issue - I got the same failure running with eclipse or from the command line with Eclipse stopped. The "fix" was to first insure my working directory had no uncommitted changes (git status was "clean"), then I deleted the local clone, and recloned from github. Then running the tests worked fine. I have no idea where the test runner was finding those v2-version files, when my grep and file explore manual looking couldn't find them. I guess a moral of this story is to not do git switch between uima v2 and v3, but instead do something that erases the local working directory, and then does a checkout again. Or perhaps using git clean or git stash --all would have worked (didn't try). See https://git-scm.com/book/en/v2/Git-Tools-Stashing-and-Cleaning -Marshall
