[RFC/PATCH] tests: optionally fail passed todo immediately

Add "--fail-passed-todo" option to stop the test immediately when a
test that is expected to fail succeeds.  After seeing the test stop,
the developer can go to the trash directory and inspect why it failed
to fail as expected.

I usually just insert "exit" after such test with an editor, but
an option like this might be easier to use.  I dunno.

Signed-off-by: Junio C Hamano <redacted>
---

 * Stopping immediately after a test that is failing (and expected
   to fail) and then going to the trash directory to inspect the
   status of the sandbox are the first two steps I often end up
   doing while fixing a bug.  It may make sense to add an option to
   cause the test to stop at a failure of test_expect_failure, but
   that is a separate topic.

 t/test-lib.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/t/test-lib.sh b/t/test-lib.sh
index f50f834..7b7cce6 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh

@@ -176,6 +176,8 @@ do
 		debug=t; shift ;;
 	-i|--i|--im|--imm|--imme|--immed|--immedi|--immedia|--immediat|--immediate)
 		immediate=t; shift ;;
+	--fail-passed-todo)
+		fail_passed_todo=t; shift ;;
 	-l|--l|--lo|--lon|--long|--long-|--long-t|--long-te|--long-tes|--long-test|--long-tests)
 		GIT_TEST_LONG=t; export GIT_TEST_LONG; shift ;;
 	-h|--h|--he|--hel|--help)

@@ -307,6 +309,7 @@ test_failure_ () {
 test_known_broken_ok_ () {
 	test_fixed=$(($test_fixed+1))
 	say_color "" "ok $test_count - $@ # TODO known breakage"
+	test "$fail_passed_todo" = "" || { GIT_EXIT_OK=t; exit 1; }
 }
 
 test_known_broken_failure_ () {

-- 
1.8.1.rc2.196.g90926c8