t5312: be more assertive about command failure

When repacking or pruning in a corrupted repository, our tests in t5312
argue that it is OK to complete the operation or bail, as long as we
don't actually delete the objects pointed to by the corruption.

This isn't a wrong line of reasoning, but the tests are a bit permissive
by using test_might_fail. The fact is that we _do_ bail currently, and
if we ever stopped doing so, that would be worthy of a human
investigating. So let's switch these to test_must_fail.

Signed-off-by: Jeff King <[email protected]>
Reviewed-by: Jonathan Tan <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

t/t5312-prune-corruption.sh

@@ -7,6 +7,9 @@ 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.
+
+Note that we do assert command failure in these cases, because that is
+what currently happens. If that changes, these tests should be revisited.
 '
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
@@ -35,7 +38,7 @@ test_expect_success 'create history reachable only from a bogus-named ref' '
 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 &&
+	test_must_fail git prune --expire=now &&
 	git cat-file -e $bogus
 '
 
@@ -53,9 +56,9 @@ test_expect_success 'non-destructive repack ignores bogus name' '
 
 test_expect_success 'destructive repack keeps packed object' '
 	create_bogus_ref &&
-	test_might_fail git repack -Ad --unpack-unreachable=now &&
+	test_must_fail git repack -Ad --unpack-unreachable=now &&
 	git cat-file -e $bogus &&
-	test_might_fail git repack -ad &&
+	test_must_fail git repack -ad &&
 	git cat-file -e $bogus
 '
 
@@ -83,7 +86,7 @@ test_expect_success 'create history with missing tip commit' '
 
 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 &&
+	test_must_fail git prune --expire=now &&
 	git cat-file -e $recoverable
 '