Subject: Re: [PATCH 3/4] t/perf: avoid testing bitmaps without lookup table

From: Junio C Hamano <[email-masked]>
Date: Thu, 17 Apr 2025 15:21:07 -0700

Taylor Blau <[email-masked]> writes:

> In a previous commit, the setting which controls whether or not the
> pack- and MIDX-bitmap machinery writes a lookup table,
> 'pack.writeBitmapLookupTable' was enabled by default.
>
> As a result, we can clean up many of our bitmap-related performance
> tests. Many of the relevant performance tests look something like:
>
>     test_it () {
>       test_expect_success 'setup pack.writeBitmapLookupTable' '
>         git config pack.writeBitmapLookupTable '"$1"'
>       '
>
>       # ...
>     }
>
>     test_it true
>     test_it false
>
> , where the two invocations of 'test_it' run the tests with and without
> bitmap lookup tables enabled.
>
> But now that lookup tables are enabled by default and have proven to be
> a performance win, let's avoid benchmarking what is now an uncommon and
> non-default scenario.
>
> Signed-off-by: Taylor Blau <[email-masked]>
> ---

Hmph, how costly are these tests to run and maintain?

I somehow have a feeling that removal of these "performance" tests
is less worrysome than removing correctness tests, but as long as we
claim to support both configurations (i.e. with and without lookup
tables), it feels a bit premature to remove tests for one of them.