kunit: test: add KUnit test runner core

Add core facilities for defining unit tests; this provides a common way
to define test cases, functions that execute code which is under test
and determine whether the code under test behaves as expected; this also
provides a way to group together related test cases in test suites (here
we call them test_modules).

Just define test cases and how to execute them for now; setting
expectations on code will be defined later.

Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/kunit/test.c

@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Base unit test (KUnit) API.
+ *
+ * Copyright (C) 2019, Google LLC.
+ * Author: Brendan Higgins <brendanhiggins@google.com>
+ */
+
+#include <kunit/test.h>
+#include <linux/kernel.h>
+
+static void kunit_set_failure(struct kunit *test)
+{
+	WRITE_ONCE(test->success, false);
+}
+
+static int kunit_vprintk_emit(int level, const char *fmt, va_list args)
+{
+	return vprintk_emit(0, level, NULL, 0, fmt, args);
+}
+
+static int kunit_printk_emit(int level, const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, fmt);
+	ret = kunit_vprintk_emit(level, fmt, args);
+	va_end(args);
+
+	return ret;
+}
+
+static void kunit_vprintk(const struct kunit *test,
+			  const char *level,
+			  struct va_format *vaf)
+{
+	kunit_printk_emit(level[1] - '0', "\t# %s: %pV", test->name, vaf);
+}
+
+static void kunit_print_tap_version(void)
+{
+	static bool kunit_has_printed_tap_version;
+
+	if (!kunit_has_printed_tap_version) {
+		kunit_printk_emit(LOGLEVEL_INFO, "TAP version 14\n");
+		kunit_has_printed_tap_version = true;
+	}
+}
+
+static size_t kunit_test_cases_len(struct kunit_case *test_cases)
+{
+	struct kunit_case *test_case;
+	size_t len = 0;
+
+	for (test_case = test_cases; test_case->run_case; test_case++)
+		len++;
+
+	return len;
+}
+
+static void kunit_print_subtest_start(struct kunit_suite *suite)
+{
+	kunit_print_tap_version();
+	kunit_printk_emit(LOGLEVEL_INFO, "\t# Subtest: %s\n", suite->name);
+	kunit_printk_emit(LOGLEVEL_INFO,
+			  "\t1..%zd\n",
+			  kunit_test_cases_len(suite->test_cases));
+}
+
+static void kunit_print_ok_not_ok(bool should_indent,
+				  bool is_ok,
+				  size_t test_number,
+				  const char *description)
+{
+	const char *indent, *ok_not_ok;
+
+	if (should_indent)
+		indent = "\t";
+	else
+		indent = "";
+
+	if (is_ok)
+		ok_not_ok = "ok";
+	else
+		ok_not_ok = "not ok";
+
+	kunit_printk_emit(LOGLEVEL_INFO,
+			  "%s%s %zd - %s\n",
+			  indent, ok_not_ok, test_number, description);
+}
+
+static bool kunit_suite_has_succeeded(struct kunit_suite *suite)
+{
+	const struct kunit_case *test_case;
+
+	for (test_case = suite->test_cases; test_case->run_case; test_case++)
+		if (!test_case->success)
+			return false;
+
+	return true;
+}
+
+static void kunit_print_subtest_end(struct kunit_suite *suite)
+{
+	static size_t kunit_suite_counter = 1;
+
+	kunit_print_ok_not_ok(false,
+			      kunit_suite_has_succeeded(suite),
+			      kunit_suite_counter++,
+			      suite->name);
+}
+
+static void kunit_print_test_case_ok_not_ok(struct kunit_case *test_case,
+					    size_t test_number)
+{
+	kunit_print_ok_not_ok(true,
+			      test_case->success,
+			      test_number,
+			      test_case->name);
+}
+
+void kunit_init_test(struct kunit *test, const char *name)
+{
+	test->name = name;
+	test->success = true;
+}
+
+/*
+ * Performs all logic to run a test case.
+ */
+static void kunit_run_case(struct kunit_suite *suite,
+			   struct kunit_case *test_case)
+{
+	struct kunit test;
+
+	kunit_init_test(&test, test_case->name);
+
+	if (suite->init) {
+		int ret;
+
+		ret = suite->init(&test);
+		if (ret) {
+			kunit_err(&test, "failed to initialize: %d\n", ret);
+			kunit_set_failure(&test);
+			test_case->success = test.success;
+			return;
+		}
+	}
+
+	test_case->run_case(&test);
+
+	if (suite->exit)
+		suite->exit(&test);
+
+	test_case->success = test.success;
+}
+
+int kunit_run_tests(struct kunit_suite *suite)
+{
+	struct kunit_case *test_case;
+	size_t test_case_count = 1;
+
+	kunit_print_subtest_start(suite);
+
+	for (test_case = suite->test_cases; test_case->run_case; test_case++) {
+		kunit_run_case(suite, test_case);
+		kunit_print_test_case_ok_not_ok(test_case, test_case_count++);
+	}
+
+	kunit_print_subtest_end(suite);
+
+	return 0;
+}
+
+void kunit_printk(const char *level,
+		  const struct kunit *test,
+		  const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	kunit_vprintk(test, level, &vaf);
+
+	va_end(args);
+}