unit-tests: show location of checks outside of tests

Checks outside of tests are caught at runtime and reported like this:

 Assertion failed: (ctx.running), function test_assert, file test-lib.c, line 267.

The assert() call aborts the unit test and doesn't reveal the location
or even the type of the offending check, as test_assert() is called by
all of them.

Handle it like the opposite case, a test without any checks: Don't
abort, but report the location of the actual check, along with a message
explaining the situation.  The output for example above becomes:

 # BUG: check outside of test at t/helper/test-example-tap.c:75

... and the unit test program continues and indicates the error in its
exit code at the end.

Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rscharfe

t/helper/test-example-tap.c

@@ -72,6 +72,8 @@ static void t_empty(void)
 
 int cmd__example_tap(int argc, const char **argv)
 {
+	check(1);
+
 	test_res = TEST(check_res = check_int(1, ==, 1), "passing test");
 	TEST(t_res(1), "passing test and assertion return 1");
 	test_res = TEST(check_res = check_int(1, ==, 2), "failing test");

t/t0080-unit-test-output.sh

@@ -7,9 +7,10 @@ TEST_PASSES_SANITIZE_LEAK=true
 
 test_expect_success 'TAP output from unit tests' - <<\EOT
 	cat >expect <<-EOF &&
+	# BUG: check outside of test at t/helper/test-example-tap.c:75
 	ok 1 - passing test
 	ok 2 - passing test and assertion return 1
-	# check "1 == 2" failed at t/helper/test-example-tap.c:77
+	# check "1 == 2" failed at t/helper/test-example-tap.c:79
 	#    left: 1
 	#   right: 2
 	not ok 3 - failing test
@@ -46,7 +47,7 @@ test_expect_success 'TAP output from unit tests' - <<\EOT
 	#    left: '\\\\'
 	#   right: '\\''
 	not ok 17 - messages from failing string and char comparison
-	# BUG: test has no checks at t/helper/test-example-tap.c:92
+	# BUG: test has no checks at t/helper/test-example-tap.c:94
 	not ok 18 - test with no checks
 	ok 19 - test with no checks returns 0
 	1..19

t/unit-tests/test-lib.c

@@ -264,7 +264,12 @@ static void test_todo(void)
 
 int test_assert(const char *location, const char *check, int ok)
 {
-	assert(ctx.running);
+	if (!ctx.running) {
+		test_msg("BUG: check outside of test at %s",
+			 make_relative(location));
+		ctx.failed = 1;
+		return 0;
+	}
 
 	if (ctx.result == RESULT_SKIP) {
 		test_msg("skipping check '%s' at %s", check,