On Tue, Apr 27 2021, Luke Shumaker wrote:

It's unclear what the purpose of t7900-subtree.sh's
`subtree_test_create_repo` helper function is.  It wraps test-lib.sh's,
`test_create_repo` but follows that up by setting log.date=relative.  Why
does it set log.date=relative?

My first guess was that at one point the tests required that, but no
longer do, and that the function is now vestigial.  I even wrote a patch
to get rid of it and was moments away from `git send-email`ing it.

However, by chance when looking for something else in the history, I
discovered the true reason, from e7aac44ed2 (contrib/subtree: ignore
log.date configuration, 2015-07-21).  It's testing that setting
log.date=relative doesn't break `git subtree`, as at one point in the past
that did break `git subtree`.

This commit message is too much about describing the journey IMO. We
could just get straight to the point, e.g. something like:

    Add a comment about why the git-subtree.sh tests set
    log.relative. It's to test that we don't have a regression of the
    bug fixed in e7aac44ed2 [...].

FWIW I think just having an isolated test for this would be better, but
since you're just refactoring existing code I think this is fine.

I.e. we'd use "git init" in the rest, and just have a test that stresses
this specifically. Or is the entry into git-subtree.sh so varied that we
need to "fuzz" all the tests like this to fully test it? I haven't
checked.