Re: [PATCH 1/6] test-lib: introduce test_commit_bulk

> Some tests need to create a string of commits. Doing this with
> test_commit is very heavy-weight, as it needs at least one process per
> commit (and in fact, uses several).
>
> For bulk creation, we can do much better by using fast-import, but it's
> often a pain to generate the input. Let's provide a helper to do so.
>
> We'll use t5310 as a guinea pig, as it has three 10-commit loops. Here
> are hyperfine results before and after:
>
>   [before]
>   Benchmark #1: ./t5310-pack-bitmaps.sh --root=/var/ram/git-tests
>     Time (mean ± σ):      2.846 s ±  0.305 s    [User: 3.042 s, System: 0.919 s]
>     Range (min … max):    2.250 s …  3.210 s    10 runs
>
>   [after]
>   Benchmark #1: ./t5310-pack-bitmaps.sh --root=/var/ram/git-tests
>     Time (mean ± σ):      2.210 s ±  0.174 s    [User: 2.570 s, System: 0.604 s]
>     Range (min … max):    1.999 s …  2.590 s    10 runs
>
> So we're over 20% faster, while making the callers slightly shorter. We
> added a lot more lines in test-lib-function.sh, of course, and the
> helper is way more featureful than we need here. But my hope is that it
> will be flexible enough to use in more places.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  t/t5310-pack-bitmaps.sh |  15 +----
>  t/test-lib-functions.sh | 131 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 134 insertions(+), 12 deletions(-)
>
> diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
> index a26c8ba9a2..3aab7024ca 100755
> --- a/t/t5310-pack-bitmaps.sh
> +++ b/t/t5310-pack-bitmaps.sh
> @@ -21,15 +21,9 @@ has_any () {
>  }
>
>  test_expect_success 'setup repo with moderate-sized history' '
> -	for i in $(test_seq 1 10)
> -	do
> -		test_commit $i
> -	done &&
> +	test_commit_bulk --id=file 10 &&
>  	git checkout -b other HEAD~5 &&
> -	for i in $(test_seq 1 10)
> -	do
> -		test_commit side-$i
> -	done &&
> +	test_commit_bulk --id=side 10 &&
>  	git checkout master &&
>  	bitmaptip=$(git rev-parse master) &&
>  	blob=$(echo tagged-blob | git hash-object -w --stdin) &&
> @@ -106,10 +100,7 @@ test_expect_success 'clone from bitmapped repository' '
>  '
>
>  test_expect_success 'setup further non-bitmapped commits' '
> -	for i in $(test_seq 1 10)
> -	do
> -		test_commit further-$i
> -	done
> +	test_commit_bulk --id=further 10
>  '
>
>  rev_list_tests 'partial bitmap'
> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
> index 0367cec5fd..32a1db81a3 100644
> --- a/t/test-lib-functions.sh
> +++ b/t/test-lib-functions.sh
> @@ -233,6 +233,137 @@ test_merge () {
>  	git tag "$1"
>  }
>
> +# Similar to test_commit, but efficiently create <nr> commits, each with a
> +# unique number $n (from 1 to <nr> by default) in the commit message.