git-commit-vandalism/t/t5312-prune-corruption.sh
Jeff King f805844676 t5312: create bogus ref as necessary
Some tests in t5312 create an illegally-named ref, and then see how
various operations handle it. But between those operations, we also do
some more setup (e.g., repacking), and we are subtly depending on how
those setup steps react to the illegal ref.

To future-proof us against those behaviors changing, let's instead
create and clean up our bogus ref on demand in the tests that need it.

This has two small extra advantages:

 - the tests are more stand-alone; we do not need an extra test to clean
   up the ref before moving on to other parts of the script

 - the creation and cleanup is together in one helper function. Because
   these depend on touching the refs in the filesystem directly, they
   may need to be tweaked for a world with alternate backends (they have
   not been noticed so far in the reftable work because with a non-file
   backend the tests don't fail; they simply become uninteresting noops
   because the broken ref isn't read at all).

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-27 12:36:44 -07:00

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#!/bin/sh
test_description='
Test pruning of repositories with minor corruptions. The goal
here is that we should always be erring on the side of safety. So
if we see, for example, a ref with a bogus name, it is OK either to
bail out or to proceed using it as a reachable tip, but it is _not_
OK to proceed as if it did not exist. Otherwise we might silently
delete objects that cannot be recovered.
'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
. ./test-lib.sh
test_expect_success 'disable reflogs' '
git config core.logallrefupdates false &&
git reflog expire --expire=all --all
'
create_bogus_ref () {
test_when_finished 'rm -f .git/refs/heads/bogus..name' &&
echo $bogus >.git/refs/heads/bogus..name
}
test_expect_success 'create history reachable only from a bogus-named ref' '
test_tick && git commit --allow-empty -m main &&
base=$(git rev-parse HEAD) &&
test_tick && git commit --allow-empty -m bogus &&
bogus=$(git rev-parse HEAD) &&
git cat-file commit $bogus >saved &&
git reset --hard HEAD^
'
test_expect_success 'pruning does not drop bogus object' '
test_when_finished "git hash-object -w -t commit saved" &&
create_bogus_ref &&
test_might_fail git prune --expire=now &&
git cat-file -e $bogus
'
test_expect_success 'put bogus object into pack' '
git tag reachable $bogus &&
git repack -ad &&
git tag -d reachable &&
git cat-file -e $bogus
'
test_expect_success 'destructive repack keeps packed object' '
create_bogus_ref &&
test_might_fail git repack -Ad --unpack-unreachable=now &&
git cat-file -e $bogus &&
test_might_fail git repack -ad &&
git cat-file -e $bogus
'
# We create two new objects here, "one" and "two". Our
# main branch points to "two", which is deleted,
# corrupting the repository. But we'd like to make sure
# that the otherwise unreachable "one" is not pruned
# (since it is the user's best bet for recovering
# from the corruption).
#
# Note that we also point HEAD somewhere besides "two",
# as we want to make sure we test the case where we
# pick up the reference to "two" by iterating the refs,
# not by resolving HEAD.
test_expect_success 'create history with missing tip commit' '
test_tick && git commit --allow-empty -m one &&
recoverable=$(git rev-parse HEAD) &&
git cat-file commit $recoverable >saved &&
test_tick && git commit --allow-empty -m two &&
missing=$(git rev-parse HEAD) &&
git checkout --detach $base &&
rm .git/objects/$(echo $missing | sed "s,..,&/,") &&
test_must_fail git cat-file -e $missing
'
test_expect_success 'pruning with a corrupted tip does not drop history' '
test_when_finished "git hash-object -w -t commit saved" &&
test_might_fail git prune --expire=now &&
git cat-file -e $recoverable
'
test_expect_success 'pack-refs does not silently delete broken loose ref' '
git pack-refs --all --prune &&
echo $missing >expect &&
git rev-parse refs/heads/main >actual &&
test_cmp expect actual
'
# we do not want to count on running pack-refs to
# actually pack it, as it is perfectly reasonable to
# skip processing a broken ref
test_expect_success 'create packed-refs file with broken ref' '
rm -f .git/refs/heads/main &&
cat >.git/packed-refs <<-EOF &&
$missing refs/heads/main
$recoverable refs/heads/other
EOF
echo $missing >expect &&
git rev-parse refs/heads/main >actual &&
test_cmp expect actual
'
test_expect_success 'pack-refs does not silently delete broken packed ref' '
git pack-refs --all --prune &&
git rev-parse refs/heads/main >actual &&
test_cmp expect actual
'
test_expect_success 'pack-refs does not drop broken refs during deletion' '
git update-ref -d refs/heads/other &&
git rev-parse refs/heads/main >actual &&
test_cmp expect actual
'
test_done