t/test-lib: allow skipping leak checks for passing tests

With `GIT_TEST_PASSING_SANITIZE_LEAK=check`, one can double check
whether a memory leak fix caused some test suites to become leak free.
This is done by running all tests with the leak checker enabled. If a
test suite does not declare `TEST_PASSES_SANITIZE_LEAK=true` but still
finishes successfully with the leak checker enabled, then this indicates
that the test is leak free and thus missing the annotation.

It is somewhat slow to execute though because it runs all of our test
suites with the leak sanitizer enabled. It is also pointless in most
cases, because the only test suites that need to be checked are those
which _aren't_ yet marked with `TEST_PASSES_SANITIZE_LEAK=true`.

Introduce a new value "check-failing". When set, we behave the same as
if "check" was passed, except that we only check those tests which do
not have `TEST_PASSES_SANITIZE_LEAK=true` set. This is significantly
faster than running all test suites but still fulfills the usecase of
finding newly-leak-free test suites.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

t/README

@@ -386,6 +386,9 @@ GIT_TEST_PASSING_SANITIZE_LEAK=check when combined with "--immediate"
 will run to completion faster, and result in the same failing
 tests.
 
+GIT_TEST_PASSING_SANITIZE_LEAK=check-failing behaves the same as "check",
+but skips all tests which are already marked as leak-free.
+
 GIT_TEST_PROTOCOL_VERSION=<n>, when set, makes 'protocol.version'
 default to n.
 

t/test-lib.sh

@@ -1558,8 +1558,16 @@ then
 		passes_sanitize_leak=t
 	fi
 
-	if test "$GIT_TEST_PASSING_SANITIZE_LEAK" = "check"
+	if test "$GIT_TEST_PASSING_SANITIZE_LEAK" = "check" ||
+	   test "$GIT_TEST_PASSING_SANITIZE_LEAK" = "check-failing"
 	then
+		if test "$GIT_TEST_PASSING_SANITIZE_LEAK" = "check-failing" &&
+		   test -n "$passes_sanitize_leak"
+		then
+			skip_all="skipping leak-free $this_test under GIT_TEST_PASSING_SANITIZE_LEAK=check-failing"
+			test_done
+		fi
+
 		sanitize_leak_check=t
 		if test -n "$invert_exit_code"
 		then
@@ -1597,6 +1605,7 @@ then
 	export LSAN_OPTIONS
 
 elif test "$GIT_TEST_PASSING_SANITIZE_LEAK" = "check" ||
+     test "$GIT_TEST_PASSING_SANITIZE_LEAK" = "check-failing" ||
      test_bool_env GIT_TEST_PASSING_SANITIZE_LEAK false
 then
 	BAIL_OUT_ENV_NEEDS_SANITIZE_LEAK "GIT_TEST_PASSING_SANITIZE_LEAK=true"