[PATCH 16/33] t3210: test for spurious error messages for dangling packed refs

[Michael Haggerty <mhagger@alum.mit.edu>]

A packed reference can be overridden by a loose reference, in which
case the packed reference is obsolete and is never used.  The object
pointed to by such a reference can be garbage collected.  Since
d66da478f2, this could lead to the emission of a spurious error
message:

    error: refs/heads/master does not point to a valid object!

The error is generated by repack_without_ref() if there is an obsolete
dangling packed reference in packed-refs when the packed-refs file has
to be rewritten due to the deletion of another packed reference.  Add
a failing test demonstrating this problem and some passing tests of
related scenarios.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---

How can I get rid of the sleeps in these tests?  I couldn't find
another portable way of reliably ensuring that commits get
garbage-collected.  (Some other tests use similar code without the
sleeps, but empirically the sleeps are necessary to get the tests to
work reliably.  Perhaps the other tests are not doing what they
think.)

 t/t3210-pack-refs.sh | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/t/t3210-pack-refs.sh b/t/t3210-pack-refs.sh
index cd04361..c032d88 100755
--- a/t/t3210-pack-refs.sh
+++ b/t/t3210-pack-refs.sh
@@ -118,4 +118,40 @@ test_expect_success 'pack, prune and repack' '
 	test_cmp all-of-them again
 '
 
+test_expect_success 'explicit pack-refs with dangling packed reference' '
+	git commit --allow-empty -m "soon to be garbage-collected" &&
+	git pack-refs --all &&
+	git reset --hard HEAD^ &&
+	sleep 1 &&
+	git reflog expire --expire=now --all &&
+	git prune --expire=now &&
+	git pack-refs --all 2>result &&
+	test_cmp /dev/null result
+'
+
+test_expect_success 'delete ref with dangling packed version' '
+	git checkout -b lamb &&
+	git commit --allow-empty -m "future garbage" &&
+	git pack-refs --all &&
+	git reset --hard HEAD^ &&
+	git checkout master &&
+	sleep 1 &&
+	git reflog expire --expire=now --all &&
+	git prune --expire=now &&
+	git branch -d lamb 2>result &&
+	test_cmp /dev/null result
+'
+
+test_expect_failure 'delete ref while another dangling packed ref' '
+	git branch lamb &&
+	git commit --allow-empty -m "future garbage" &&
+	git pack-refs --all &&
+	git reset --hard HEAD^ &&
+	sleep 1 &&
+	git reflog expire --expire=now --all &&
+	git prune --expire=now &&
+	git branch -d lamb 2>result &&
+	test_cmp /dev/null result
+'
+
 test_done
-- 
1.8.2.1