You generally create the test in a new file that won't be affected by checking out older code. If you need to change some part of your build system or test syst

You generally create the test in a new file that won't be affected by checking out older code. If you need to change some part of your build system or test system, have the test be a patch that can be applied, run the build, run the tests, and check the results. As far as having other uncommitted changes; just stash those. "git stash" is a tool you should use very often for any time you have uncommitted work that you need to clear out before doing some other git operation.