[PATCH v2 2/2] kunit: add KUnit test to assert kernel state before KUnit suites are run

add pre-defined KUnit test suite and test case that asserts both
`debug_locks` and `TAINT_WARN` prior to running any (user) KUnit tests.
This asserts integrity before tests are run.

Signed-off-by: Malte Wechter <[email protected]>
---
 lib/kunit/executor.c |  8 +++++++-
 lib/kunit/test.c     | 30 ++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c
index b0f8a41d61d36..0db67fe7f09f9 100644
--- a/lib/kunit/executor.c
+++ b/lib/kunit/executor.c
@@ -290,9 +290,15 @@ void kunit_exec_run_tests(struct kunit_suite_set *suite_set, bool builtin)
 	size_t num_suites = suite_set->end - suite_set->start;
 	bool autorun = kunit_autorun();
 
+	#ifdef CONFIG_KUNIT_EXTRA_ASSERTS
+	size_t num_suites_plus_extra = num_suites+1;
+	#else
+	size_t num_suites_plus_extra = num_suites;
+	#endif
+
 	if (autorun && (builtin || num_suites)) {
 		pr_info("KTAP version 1\n");
-		pr_info("1..%zu\n", num_suites);
+		pr_info("1..%zu\n", num_suites_plus_extra);
 	}
 
 	__kunit_test_suites_init(suite_set->start, num_suites, autorun);
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 99773e000e1b7..e64c6d1575280 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -835,6 +835,30 @@ bool kunit_enabled(void)
 	return enable_param;
 }
 
+#ifdef CONFIG_KUNIT_EXTRA_ASSERTS
+#define DEBUG_LOCKS_OK 1
+#define TAINT_WARN_OK 0
+
+static void pre_kunit_assert(struct kunit *test)
+{
+	KUNIT_EXPECT_EQ_MSG(test, debug_locks, DEBUG_LOCKS_OK,
+		"debug_locks are off before any test ran");
+	KUNIT_EXPECT_EQ_MSG(test, test_taint(TAINT_WARN), TAINT_WARN_OK,
+		"kernel already TAINT_WARN tainted before any test ran");
+}
+
+static struct kunit_case pre_kunit_assert_cases[] = {
+	KUNIT_CASE(pre_kunit_assert),
+	{}
+};
+
+static struct kunit_suite pre_kunit_assert_clean_state_suite = {
+	.name = "pre_kunit_extra_asserts",
+	.test_cases = pre_kunit_assert_cases,
+};
+
+#endif /* CONFIG_RUST_KUNIT_EXTRA_ASSERTS */
+
 int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_suites,
 			     bool run_tests)
 {
@@ -857,6 +881,12 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
 	}
 	static_branch_inc(&kunit_running);
 
+	#ifdef CONFIG_KUNIT_EXTRA_ASSERTS
+	kunit_init_suite(&pre_kunit_assert_clean_state_suite);
+	if (run_tests)
+		kunit_run_tests(&pre_kunit_assert_clean_state_suite);
+	#endif
+
 	for (i = 0; i < num_suites; i++) {
 		kunit_init_suite(suites[i]);
 		if (run_tests)

-- 
2.51.2