[PATCH v3] Test fsck a bit harder

git-fsck, of all tools, has very few tests.  This adds some more:
* a corrupted object;
* a branch pointing to a non-commit;
* a tag pointing to a nonexistent object;
* and a tag pointing to an object of a type other than what the tag
  itself claims.

Signed-off-by: Thomas Rast <redacted>
---

I investigated the test failures with v2, and it turns out the problem
was in my use of hash-object.  When correctly passing '-t tag' for the
tags, fsck does detect the breakage.  So here's an updated version of
this test.  Interdiff:

  diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
  index 628db19..a22632f 100755
  --- a/t/t1450-fsck.sh
  +++ b/t/t1450-fsck.sh
  @@ -66,13 +66,13 @@ tagger T A Gger [off-list ref] 1234567890 -0000
   This is an invalid tag.
   EOF

  -test_expect_success 'tag pointing to nonexistent' '
  -       tag=$(git hash-object -t tag -w --stdin < invalid-tag) &&
  +test_expect_failure 'tag pointing to nonexistent' '
  +       tag=$(git hash-object -w --stdin < invalid-tag) &&
          echo $tag > .git/refs/tags/invalid &&
  -       git fsck 2>&1 | tee out &&
  -       grep "missing commit ffffffffffffffffffffffffffffffffffffffff" out &&
  -       rm .git/refs/tags/invalid &&
  -       rm -f .git/objects/$(echo $tag | sed "s#^..#&/#")
  +       git fsck --tags 2>out &&
  +       cat out &&
  +       grep "could not load tagged object" out &&
  +       rm .git/refs/tags/invalid
   '

   cat > wrong-tag <<EOF
  @@ -84,11 +84,12 @@ tagger T A Gger [off-list ref] 1234567890 -0000
   This is an invalid tag.
   EOF

  -test_expect_success 'tag pointing to something else than its type' '
  -       tag=$(git hash-object -t tag -w --stdin < wrong-tag) &&
  +test_expect_failure 'tag pointing to something else than its type' '
  +       tag=$(git hash-object -w --stdin < wrong-tag) &&
          echo $tag > .git/refs/tags/wrong &&
  -       git fsck 2>&1 | tee out &&
  -       grep "Object.*is a blob, not a commit" out &&
  +       git fsck --tags 2>out &&
  +       cat out &&
  +       grep "some sane error message" out &&
          rm .git/refs/tags/wrong
   '

 t/t1450-fsck.sh |   66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 66 insertions(+), 0 deletions(-)

diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index 4597af0..628db19 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh

@@ -28,4 +28,70 @@ test_expect_success 'loose objects borrowed from alternate are not missing' '
 	)
 '
 
+# Corruption tests follow.  Make sure to remove all traces of the
+# specific corruption you test afterwards, lest a later test trip over
+# it.
+
+test_expect_success 'object with bad sha1' '
+	sha=$(echo blob | git hash-object -w --stdin) &&
+	echo $sha &&
+	old=$(echo $sha | sed "s+^..+&/+") &&
+	new=$(dirname $old)/ffffffffffffffffffffffffffffffffffffff &&
+	sha="$(dirname $new)$(basename $new)"
+	mv .git/objects/$old .git/objects/$new &&
+	git update-index --add --cacheinfo 100644 $sha foo &&
+	tree=$(git write-tree) &&
+	cmt=$(echo bogus | git commit-tree $tree) &&
+	git update-ref refs/heads/bogus $cmt &&
+	(git fsck 2>out; true) &&
+	grep "$sha.*corrupt" out &&
+	rm -f .git/objects/$new &&
+	git update-ref -d refs/heads/bogus &&
+	git read-tree -u --reset HEAD
+'
+
+test_expect_success 'branch pointing to non-commit' '
+	git rev-parse HEAD^{tree} > .git/refs/heads/invalid &&
+	git fsck 2>out &&
+	grep "not a commit" out &&
+	git update-ref -d refs/heads/invalid
+'
+
+cat > invalid-tag <<EOF
+object ffffffffffffffffffffffffffffffffffffffff
+type commit
+tag invalid
+tagger T A Gger <tagger@example.com> 1234567890 -0000
+
+This is an invalid tag.
+EOF
+
+test_expect_success 'tag pointing to nonexistent' '
+	tag=$(git hash-object -t tag -w --stdin < invalid-tag) &&
+	echo $tag > .git/refs/tags/invalid &&
+	git fsck 2>&1 | tee out &&
+	grep "missing commit ffffffffffffffffffffffffffffffffffffffff" out &&
+	rm .git/refs/tags/invalid &&
+	rm -f .git/objects/$(echo $tag | sed "s#^..#&/#")
+'
+
+cat > wrong-tag <<EOF
+object $(echo blob | git hash-object -w --stdin)
+type commit
+tag wrong
+tagger T A Gger <tagger@example.com> 1234567890 -0000
+
+This is an invalid tag.
+EOF
+
+test_expect_success 'tag pointing to something else than its type' '
+	tag=$(git hash-object -t tag -w --stdin < wrong-tag) &&
+	echo $tag > .git/refs/tags/wrong &&
+	git fsck 2>&1 | tee out &&
+	grep "Object.*is a blob, not a commit" out &&
+	rm .git/refs/tags/wrong
+'
+
+
+
 test_done

-- 
1.6.2.rc1.310.g364d6