Re: [PATCH v3 1/2] difftool: add a skeleton for the upcoming builtin

On Sat, Nov 26, 2016 at 02:01:36PM +0100, Johannes Schindelin wrote:

quoted

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