t7700: add tests for --keep-unreachable

We don't have any tests for `git repack --keep-unreachable`. Add three
tests that exercise its behaviour with different packed states for the
unreachable object.

Note that the last test is failing. This will be fixed in the next
commit.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

t/t7700-repack.sh

@@ -826,4 +826,77 @@ test_expect_success '-n overrides repack.updateServerInfo=true' '
 	test_server_info_missing
 '
 
+expect_object_count () {
+	find .git/objects \( -type d \( -name pack -o -name info \) -prune \) -o -type f -print >objects &&
+	test_line_count = "$1" objects
+}
+
+expect_object_in_idx () {
+	git verify-pack -v "$1" >objects &&
+	test_grep "^$2" objects
+}
+
+test_expect_success '--keep-unreachable appends unreachable packed objects to new pack' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git config set core.logAllRefUpdates false &&
+
+		# Set up the repo so that all objects, including the
+		# unreachable one, are packed.
+		test_commit --no-tag unreachable &&
+		git repack -ad &&
+		expect_object_count 0 &&
+		unreachable_oid=$(git rev-parse --verify HEAD) &&
+		git commit --amend --message rewritten &&
+
+		git repack -ad --keep-unreachable &&
+		expect_object_count 0 &&
+		expect_object_in_idx .git/objects/pack/*.idx "$unreachable_oid"
+	)
+'
+
+test_expect_success '--keep-unreachable packs unreachable loose object with existing packs' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git config set core.logAllRefUpdates false &&
+
+		# Set up the repo so that we have an existing packfile with
+		# reachable objects, only. The unreachable object as well as
+		# the rewritten commit are both loose.
+		test_commit --no-tag initial &&
+		git repack -ad &&
+		git commit --amend --message unreachable &&
+		unreachable_oid=$(git rev-parse --verify HEAD) &&
+		git commit --amend --message rewritten &&
+		expect_object_count 2 &&
+
+		git repack -ad --keep-unreachable &&
+		expect_object_count 0 &&
+		expect_object_in_idx .git/objects/pack/*.idx "$unreachable_oid"
+	)
+'
+
+test_expect_failure '--keep-unreachable packs unreachable loose object without existing packs' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git config set core.logAllRefUpdates false &&
+
+		# Set up the repo so that all objects are unpacked.
+		test_commit --no-tag unreachable &&
+		unreachable_oid=$(git rev-parse --verify HEAD) &&
+		git commit --amend --message rewritten &&
+		expect_object_count 4 &&
+
+		git repack -ad --keep-unreachable &&
+		expect_object_count 0 &&
+		expect_object_in_idx .git/objects/pack/*.idx "$unreachable_oid"
+	)
+'
+
 test_done