fsck tests: refactor one test to use a sub-repo

Refactor one of the fsck tests to use a throwaway repository. It's a
pervasive pattern in t1450-fsck.sh to spend a lot of effort on the
teardown of a tests so we're not leaving corrupt content for the next
test.

We can instead use the pattern of creating a named sub-repository,
then we don't have to worry about cleaning up after ourselves, nobody
will care what state the broken "hash-mismatch" repository is after
this test runs.

See [1] for related discussion on various "modern" test patterns that
can be used to avoid verbosity and increase reliability.

1. https://lore.kernel.org/git/[email protected]/

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

t/t1450-fsck.sh

@@ -48,24 +48,25 @@ remove_object () {
 	rm "$(sha1_file "$1")"
 }
 
-test_expect_success 'object with bad sha1' '
-	sha=$(echo blob | git hash-object -w --stdin) &&
-	old=$(test_oid_to_path "$sha") &&
-	new=$(dirname $old)/$(test_oid ff_2) &&
-	sha="$(dirname $new)$(basename $new)" &&
-	mv .git/objects/$old .git/objects/$new &&
-	test_when_finished "remove_object $sha" &&
-	git update-index --add --cacheinfo 100644 $sha foo &&
-	test_when_finished "git read-tree -u --reset HEAD" &&
-	tree=$(git write-tree) &&
-	test_when_finished "remove_object $tree" &&
-	cmt=$(echo bogus | git commit-tree $tree) &&
-	test_when_finished "remove_object $cmt" &&
-	git update-ref refs/heads/bogus $cmt &&
-	test_when_finished "git update-ref -d refs/heads/bogus" &&
+test_expect_success 'object with hash mismatch' '
+	git init --bare hash-mismatch &&
+	(
+		cd hash-mismatch &&
 
-	test_must_fail git fsck 2>out &&
-	test_i18ngrep "$sha.*corrupt" out
+		oid=$(echo blob | git hash-object -w --stdin) &&
+		old=$(test_oid_to_path "$oid") &&
+		new=$(dirname $old)/$(test_oid ff_2) &&
+		oid="$(dirname $new)$(basename $new)" &&
+
+		mv objects/$old objects/$new &&
+		git update-index --add --cacheinfo 100644 $oid foo &&
+		tree=$(git write-tree) &&
+		cmt=$(echo bogus | git commit-tree $tree) &&
+		git update-ref refs/heads/bogus $cmt &&
+
+		test_must_fail git fsck 2>out &&
+		grep "$oid.*corrupt" out
+	)
 '
 
 test_expect_success 'branch pointing to non-commit' '