[PATCH net-next v2 3/4] selftests: kselftest_harness: support using xfail

[Jakub Kicinski <kuba@kernel.org>]

Selftest summary includes XFAIL but there's no way to use
it from within the harness. Support it in a similar way to skip.

Currently tests report skip for things they expect to fail
e.g. when given combination of parameters is known to be unsupported.
This is confusing because in an ideal environment and fully featured
kernel no tests should be skipped.

Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2: fix alignment of the reason (remove one space after XFAIL)
---
 tools/testing/selftests/kselftest_harness.h | 37 +++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index 618b41eac749..04177813930b 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -141,6 +141,33 @@
 	statement; \
 } while (0)
 
+/**
+ * XFAIL()
+ *
+ * @statement: statement to run after reporting XFAIL
+ * @fmt: format string
+ * @...: optional arguments
+ *
+ * .. code-block:: c
+ *
+ *     XFAIL(statement, fmt, ...);
+ *
+ * This forces a "pass" after reporting why something is expected to fail,
+ * and runs "statement", which is usually "return" or "goto skip".
+ */
+#define XFAIL(statement, fmt, ...) do { \
+	snprintf(_metadata->results->reason, \
+		 sizeof(_metadata->results->reason), fmt, ##__VA_ARGS__); \
+	if (TH_LOG_ENABLED) { \
+		fprintf(TH_LOG_STREAM, "#      XFAIL     %s\n", \
+			_metadata->results->reason); \
+	} \
+	_metadata->passed = 1; \
+	_metadata->xfail = 1; \
+	_metadata->trigger = 0; \
+	statement; \
+} while (0)
+
 /**
  * TEST() - Defines the test function and creates the registration
  * stub
@@ -834,6 +861,7 @@ struct __test_metadata {
 	int termsig;
 	int passed;
 	int skip;	/* did SKIP get used? */
+	int xfail;	/* did XFAIL get used? */
 	int trigger; /* extra handler after the evaluation */
 	int timeout;	/* seconds to wait for test timeout */
 	bool timed_out;	/* did this test timeout instead of exiting? */
@@ -941,6 +969,9 @@ void __wait_for_test(struct __test_metadata *t)
 			/* SKIP */
 			t->passed = 1;
 			t->skip = 1;
+		} else if (WEXITSTATUS(status) == KSFT_XFAIL) {
+			t->passed = 1;
+			t->xfail = 1;
 		} else if (t->termsig != -1) {
 			t->passed = 0;
 			fprintf(TH_LOG_STREAM,
@@ -1112,6 +1143,7 @@ void __run_test(struct __fixture_metadata *f,
 	/* reset test struct */
 	t->passed = 1;
 	t->skip = 0;
+	t->xfail = 0;
 	t->trigger = 0;
 	t->no_print = 0;
 	memset(t->results->reason, 0, sizeof(t->results->reason));
@@ -1133,6 +1165,8 @@ void __run_test(struct __fixture_metadata *f,
 		t->fn(t, variant);
 		if (t->skip)
 			_exit(KSFT_SKIP);
+		if (t->xfail)
+			_exit(KSFT_XFAIL);
 		if (t->passed)
 			_exit(KSFT_PASS);
 		/* Something else happened. */
@@ -1146,6 +1180,9 @@ void __run_test(struct __fixture_metadata *f,
 	if (t->skip)
 		ksft_test_result_skip("%s\n", t->results->reason[0] ?
 					t->results->reason : "unknown");
+	else if (t->xfail)
+		ksft_test_result_xfail("%s\n", t->results->reason[0] ?
+				       t->results->reason : "unknown");
 	else
 		ksft_test_result(t->passed, "%s%s%s.%s\n",
 			f->name, variant->name[0] ? "." : "", variant->name, t->name);
-- 
2.43.0