kunit: Print test statistics on failure

When a number of tests fail, it can be useful to get higher-level
statistics of how many tests are failing (or how many parameters are
failing in parameterised tests), and in what cases or suites. This is
already done by some non-KUnit tests, so add support for automatically
generating these for KUnit tests.

This change adds a 'kunit_stats_enabled' switch which has three values:
- 0: No stats are printed (current behaviour)
- 1: Stats are printed only for tests/suites with more than one
     subtests, and at least one failure (new default)
- 2: Always print test statistics

For parameterised tests, the summary line looks as follows:
"    # inode_test_xtimestamp_decoding: 0 / 16 test parameters failed"
For test suites, it looks like this:
"# ext4_inode_test: (0 / 1) tests failed (0 / 16 test parameters)"

kunit_tool is also updated to correctly ignore diagnostic lines, so that
these statistics do not prevent the result from parsing.

Signed-off-by: David Gow <davidgow@google.com>

lib/kunit/test.c

@@ -9,13 +9,48 @@
 #include <kunit/test.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
+#include <linux/moduleparam.h>
 #include <linux/sched/debug.h>
 #include <linux/sched.h>
 
 #include "debugfs.h"
 #include "string-stream.h"
 #include "try-catch-impl.h"
 
+/*
+ * KUnit statistic mode:
+ * 0 - disabled
+ * 1 - only when there is at least one failure, and more than one subtest
+ * 2 - enabled
+ */
+static int kunit_stats_enabled = 1;
+core_param(kunit_stats_enabled, kunit_stats_enabled, int, 0644);
+
+static bool kunit_should_print_stats(int num_failures, int num_subtests)
+{
+	if (kunit_stats_enabled == 0)
+		return false;
+
+	if (kunit_stats_enabled == 2)
+		return true;
+
+	return (num_failures > 0 && num_subtests > 1);
+}
+
+static void kunit_print_test_stats(struct kunit *test,
+				   size_t num_failures, size_t num_subtests)
+{
+	if (!kunit_should_print_stats(num_failures, num_subtests))
+		return;
+
+	kunit_log(KERN_INFO, test,
+		  KUNIT_SUBTEST_INDENT
+		  "# %s: %lu / %lu test parameters failed",
+		  test->name,
+		  num_failures,
+		  num_subtests);
+}
+
 /*
  * Append formatted message to log, size of which is limited to
  * KUNIT_LOG_SIZE bytes (including null terminating byte).
@@ -346,15 +381,37 @@ static void kunit_run_case_catch_errors(struct kunit_suite *suite,
 	test_case->success = test->success;
 }
 
+static void kunit_print_suite_stats(struct kunit_suite *suite,
+				    size_t num_failures,
+				    size_t total_param_failures,
+				    size_t total_params)
+{
+	size_t num_cases = kunit_suite_num_test_cases(suite);
+
+	if (!kunit_should_print_stats(num_failures, num_cases))
+		return;
+
+	kunit_log(KERN_INFO, suite,
+		  "# %s: (%lu / %lu) tests failed (%lu / %lu test parameters)",
+		  suite->name,
+		  num_failures,
+		  num_cases,
+		  total_param_failures,
+		  total_params);
+}
+
 int kunit_run_tests(struct kunit_suite *suite)
 {
 	char param_desc[KUNIT_PARAM_DESC_SIZE];
 	struct kunit_case *test_case;
+	size_t num_suite_failures = 0;
+	size_t total_param_failures = 0, total_params = 0;
 
 	kunit_print_subtest_start(suite);
 
 	kunit_suite_for_each_test_case(suite, test_case) {
 		struct kunit test = { .param_value = NULL, .param_index = 0 };
+		size_t num_params = 0, num_failures = 0;
 		bool test_success = true;
 
 		if (test_case->generate_params) {
@@ -385,13 +442,27 @@ int kunit_run_tests(struct kunit_suite *suite)
 				test.param_value = test_case->generate_params(test.param_value, param_desc);
 				test.param_index++;
 			}
+
+			if (!test.success)
+				num_failures++;
+			num_params++;
+
 		} while (test.param_value);
 
+		kunit_print_test_stats(&test, num_failures, num_params);
+
 		kunit_print_ok_not_ok(&test, true, test_success,
 				      kunit_test_case_num(suite, test_case),
 				      test_case->name);
+
+		if (!test_success)
+			num_suite_failures++;
+		total_params += num_params;
+		total_param_failures += num_failures;
 	}
 
+	kunit_print_suite_stats(suite, num_suite_failures,
+				total_param_failures, total_params);
 	kunit_print_subtest_end(suite);
 
 	return 0;

tools/testing/kunit/kunit_parser.py

@@ -95,7 +95,7 @@ def print_log(log):
 	for m in log:
 		print_with_timestamp(m)
 
-TAP_ENTRIES = re.compile(r'^(TAP|[\s]*ok|[\s]*not ok|[\s]*[0-9]+\.\.[0-9]+|[\s]*#).*$')
+TAP_ENTRIES = re.compile(r'^(TAP|[\s]*ok|[\s]*not ok|[\s]*[0-9]+\.\.[0-9]+|[\s]*# Subtest:).*$')
 
 def consume_non_diagnositic(lines: List[str]) -> None:
 	while lines and not TAP_ENTRIES.match(lines[0]):