On Sat, Nov 26, 2016 at 02:01:36PM +0100, Johannes Schindelin wrote: > > If you want to control it from outside the test script, you'd need > > something like: > > > > if test "$GIT_TEST_DIFFTOOL" = "builtin" > > That is a bit magic. I first used "GIT_USE_BUILTIN_DIFFTOOL" and it did > not work. My name is arguably more correct (see also Jakub's note about > "naming is hard"), but yours works because there is a "TEST" substring in > it. Yes. You are free to add an exception to the env list in test-lib.sh, but we usually use GIT_TEST_* to avoid having to do so. -Peff