Re: [RFC/PATCH] Makefile: add test-all target

Jeff King [off-list ref] writes:

I'm don't have strong feelings on it either way. But if we think those
tests are worth running in CI, then...

quoted

So I am tempted to do

test-extra: all
	$(MAKE) -C contrib/credential/netrc test
	$(MAKE) -C contrib/diff-highlight test
	: $(MAKE) -C contrib/mw-to-git test
	$(MAKE) -C contrib/subtree test

...we'd probably want to keep running mw-to-git tests, and teach one of
the CI environments to install the appropriate perl modules to avoid
skipping them.

I saw netrc credential helper break on one of the jobs that lack
Perl, so the test there needs to be fixed before we can include it
in test-extra.