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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 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'