[PATCH v2 1/4] test-tool: help verifying BUG() code paths

[Johannes Schindelin <johannes.schindelin@gmx.de>]

When we call BUG(), we signal via SIGABRT that something bad happened,
dumping cores if so configured. In some setups these coredumps are
redirected to some central place such as /proc/sys/kernel/core_pattern,
which is a good thing.

However, when we try to verify in our test suite that bugs are caught in
certain code paths, we do *not* want to clutter such a central place
with unnecessary coredumps.

So let's special-case the test helpers (which we use to verify such code
paths) so that the BUG() calls will *not* call abort() but exit with a
special-purpose exit code instead.

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 t/helper/test-tool.c | 2 ++
 usage.c              | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 87066ced62a..5176f9f20ae 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -47,7 +47,9 @@ static struct test_cmd cmds[] = {
 int cmd_main(int argc, const char **argv)
 {
 	int i;
+	extern int BUG_exit_code;
 
+	BUG_exit_code = 99;
 	if (argc < 2)
 		die("I need a test name!");
 
diff --git a/usage.c b/usage.c
index cdd534c9dfc..9c84dccfa97 100644
--- a/usage.c
+++ b/usage.c
@@ -210,6 +210,9 @@ void warning(const char *warn, ...)
 	va_end(params);
 }
 
+/* Only set this, ever, from t/helper/, when verifying that bugs are caught. */
+int BUG_exit_code;
+
 static NORETURN void BUG_vfl(const char *file, int line, const char *fmt, va_list params)
 {
 	char prefix[256];
@@ -221,6 +224,8 @@ static NORETURN void BUG_vfl(const char *file, int line, const char *fmt, va_lis
 		snprintf(prefix, sizeof(prefix), "BUG: ");
 
 	vreportf(prefix, fmt, params);
+	if (BUG_exit_code)
+		exit(BUG_exit_code);
 	abort();
 }
 
-- 
2.17.0.windows.1.36.gdf4ca5fb72a