t: add basic bitmap functionality tests

Now that we can read and write bitmaps, we can exercise them
with some basic functionality tests. These tests aren't
particularly useful for seeing the benefit, as the test
repo is too small for it to make a difference. However, we
can at least check that using bitmaps does not break anything.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5310-pack-bitmaps.sh

@@ -0,0 +1,138 @@
+#!/bin/sh
+
+test_description='exercise basic bitmap functionality'
+. ./test-lib.sh
+
+test_expect_success 'setup repo with moderate-sized history' '
+	for i in $(test_seq 1 10); do
+		test_commit $i
+	done &&
+	git checkout -b other HEAD~5 &&
+	for i in $(test_seq 1 10); do
+		test_commit side-$i
+	done &&
+	git checkout master &&
+	blob=$(echo tagged-blob | git hash-object -w --stdin) &&
+	git tag tagged-blob $blob &&
+	git config pack.writebitmaps true
+'
+
+test_expect_success 'full repack creates bitmaps' '
+	git repack -ad &&
+	ls .git/objects/pack/ | grep bitmap >output &&
+	test_line_count = 1 output
+'
+
+test_expect_success 'rev-list --test-bitmap verifies bitmaps' '
+	git rev-list --test-bitmap HEAD
+'
+
+rev_list_tests() {
+	state=$1
+
+	test_expect_success "counting commits via bitmap ($state)" '
+		git rev-list --count HEAD >expect &&
+		git rev-list --use-bitmap-index --count HEAD >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "counting partial commits via bitmap ($state)" '
+		git rev-list --count HEAD~5..HEAD >expect &&
+		git rev-list --use-bitmap-index --count HEAD~5..HEAD >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "counting non-linear history ($state)" '
+		git rev-list --count other...master >expect &&
+		git rev-list --use-bitmap-index --count other...master >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "enumerate --objects ($state)" '
+		git rev-list --objects --use-bitmap-index HEAD >tmp &&
+		cut -d" " -f1 <tmp >tmp2 &&
+		sort <tmp2 >actual &&
+		git rev-list --objects HEAD >tmp &&
+		cut -d" " -f1 <tmp >tmp2 &&
+		sort <tmp2 >expect &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "bitmap --objects handles non-commit objects ($state)" '
+		git rev-list --objects --use-bitmap-index HEAD tagged-blob >actual &&
+		grep $blob actual
+	'
+}
+
+rev_list_tests 'full bitmap'
+
+test_expect_success 'clone from bitmapped repository' '
+	git clone --no-local --bare . clone.git &&
+	git rev-parse HEAD >expect &&
+	git --git-dir=clone.git rev-parse HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'setup further non-bitmapped commits' '
+	for i in $(test_seq 1 10); do
+		test_commit further-$i
+	done
+'
+
+rev_list_tests 'partial bitmap'
+
+test_expect_success 'fetch (partial bitmap)' '
+	git --git-dir=clone.git fetch origin master:master &&
+	git rev-parse HEAD >expect &&
+	git --git-dir=clone.git rev-parse HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'incremental repack cannot create bitmaps' '
+	test_commit more-1 &&
+	test_must_fail git repack -d
+'
+
+test_expect_success 'incremental repack can disable bitmaps' '
+	test_commit more-2 &&
+	git repack -d --no-write-bitmap-index
+'
+
+test_expect_success 'full repack, reusing previous bitmaps' '
+	git repack -ad &&
+	ls .git/objects/pack/ | grep bitmap >output &&
+	test_line_count = 1 output
+'
+
+test_expect_success 'fetch (full bitmap)' '
+	git --git-dir=clone.git fetch origin master:master &&
+	git rev-parse HEAD >expect &&
+	git --git-dir=clone.git rev-parse HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_lazy_prereq JGIT '
+	type jgit
+'
+
+test_expect_success JGIT 'we can read jgit bitmaps' '
+	git clone . compat-jgit &&
+	(
+		cd compat-jgit &&
+		rm -f .git/objects/pack/*.bitmap &&
+		jgit gc &&
+		git rev-list --test-bitmap HEAD
+	)
+'
+
+test_expect_success JGIT 'jgit can read our bitmaps' '
+	git clone . compat-us &&
+	(
+		cd compat-us &&
+		git repack -adb &&
+		# jgit gc will barf if it does not like our bitmaps
+		jgit gc
+	)
+'
+
+test_done