t5309: create failing test for 'git index-pack'

This new test demonstrates some behavior where a valid packfile is being
rejected by the Git client due to the order in which it is resolving
REF_DELTAs.

The thin packfile has a REF_DELTA chain A->B->C where C is not included
in the packfile. However, the client repository contains both C and B
already. Thus, 'git index-pack' is able to resolve A before resolving B.

When resolving B, it then attempts to resolve any other REF_DELTAs that
are pointing to B as a base. This "revisits" A and complains as if there
is a cycle, but it did not actually detect a cycle.

A fix will arrive in the next change.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/t5309-pack-delta-cycles.sh b/t/t5309-pack-delta-cycles.sh
index 60fc710bacb20e558a6c445969352e4aac08fd90..6a9367633026c1aa81d5adbda5d11084046b25db 100755 (executable)
--- a/t/t5309-pack-delta-cycles.sh
+++ b/t/t5309-pack-delta-cycles.sh
@@ -75,4 +75,28 @@ test_expect_success 'failover to a duplicate object in the same pack' '
        test_must_fail git index-pack --fix-thin --stdin <recoverable.pack
 '
 
+test_expect_failure 'index-pack works with thin pack A->B->C with B on disk' '
+       git init server &&
+       (
+               cd server &&
+               test_commit_bulk 4
+       ) &&
+
+       A=$(git -C server rev-parse HEAD^{tree}) &&
+       B=$(git -C server rev-parse HEAD~1^{tree}) &&
+       C=$(git -C server rev-parse HEAD~2^{tree}) &&
+       git -C server reset --hard HEAD~1 &&
+
+       test-tool -C server pack-deltas --num-objects=2 >thin.pack <<-EOF &&
+       REF_DELTA $A $B
+       REF_DELTA $B $C
+       EOF
+
+       git clone "file://$(pwd)/server" client &&
+       (
+               cd client &&
+               git index-pack --fix-thin --stdin <../thin.pack
+       )
+'
+
 test_done