Subject: Re: [PATCH] t1092: use GIT_PROGRESS_DELAY for consistent results

From: Junio C Hamano <[email-masked]>
Date: Tue, 25 May 2021 11:41:04 +0900

Derrick Stolee <[email-masked]> writes:

> The test is comparing the same exact Git command just with
> different configurations. Any change to what Git writes to
> stderr should be consistent across these, unless there is
> an explicit reason why it would behave differently across
> these options (for example, saying "You are in a sparse
> checkout" in 'git status').
>
> There are no expectations that stderr is stable across
> versions of Git. These tests don't add friction to developers
> making new features or changing the error messages that appear
> over stderr. It's just that these tests should catch any
> unintended inconsistency across these modes.

If it just happens that an auto-gc gets triggered, and millions of
other similar reasons in the future, will break that expectation,
without running two different vintages of Git.

I agree with Jonathan that it fundamentally is flakey to expect two
invocations of Git will behave exactly the same.  Even repacking a
repository starting from exactly the same state into a single pack
may not produce byte-for-byte identical result due to thread
scheduling.