selftests: Add header documentation and helpers

Add "how to use this API" documentation to kselftest.h, and include some
addition helpers and notes to make things easier to use.

Additionally removes the incorrect "Bail out!" line from the standard exit
path. The TAP13 specification says that "Bail out!"  should be used when
giving up before all tests have been run. For a "normal" execution run,
the selftests should not report "Bail out!".
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/kselftest.h

@@ -6,6 +6,37 @@
  * Copyright (c) 2014 Shuah Khan <shuahkh@osg.samsung.com>
  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
  *
+ * Using this API consists of first counting how many tests your code
+ * has to run, and then starting up the reporting:
+ *
+ *     ksft_print_header();
+ *     ksft_set_plan(total_number_of_tests);
+ *
+ * For each test, report any progress, debugging, etc with:
+ *
+ *     ksft_print_msg(fmt, ...);
+ *
+ * and finally report the pass/fail/skip/xfail state of the test with one of:
+ *
+ *     ksft_test_result(condition, fmt, ...);
+ *     ksft_test_result_pass(fmt, ...);
+ *     ksft_test_result_fail(fmt, ...);
+ *     ksft_test_result_skip(fmt, ...);
+ *     ksft_test_result_xfail(fmt, ...);
+ *     ksft_test_result_error(fmt, ...);
+ *
+ * When all tests are finished, clean up and exit the program with one of:
+ *
+ *    ksft_exit(condition);
+ *    ksft_exit_pass();
+ *    ksft_exit_fail();
+ *
+ * If the program wants to report details on why the entire program has
+ * failed, it can instead exit with a message (this is usually done when
+ * the program is aborting before finishing all tests):
+ *
+ *    ksft_exit_fail_msg(fmt, ...);
+ *
  */
 #ifndef __KSELFTEST_H
 #define __KSELFTEST_H
@@ -74,7 +105,7 @@ static inline void ksft_print_cnts(void)
 	if (ksft_plan != ksft_test_num())
 		printf("# Planned tests != run tests (%u != %u)\n",
 			ksft_plan, ksft_test_num());
-	printf("# Pass %d Fail %d Xfail %d Xpass %d Skip %d Error %d\n",
+	printf("# Totals: pass:%d fail:%d xfail:%d xpass:%d skip:%d error:%d\n",
 		ksft_cnt.ksft_pass, ksft_cnt.ksft_fail,
 		ksft_cnt.ksft_xfail, ksft_cnt.ksft_xpass,
 		ksft_cnt.ksft_xskip, ksft_cnt.ksft_error);
@@ -120,6 +151,32 @@ static inline void ksft_test_result_fail(const char *msg, ...)
 	va_end(args);
 }
 
+/**
+ * ksft_test_result() - Report test success based on truth of condition
+ *
+ * @condition: if true, report test success, otherwise failure.
+ */
+#define ksft_test_result(condition, fmt, ...) do {	\
+	if (!!(condition))				\
+		ksft_test_result_pass(fmt, ##__VA_ARGS__);\
+	else						\
+		ksft_test_result_fail(fmt, ##__VA_ARGS__);\
+	} while (0)
+
+static inline void ksft_test_result_xfail(const char *msg, ...)
+{
+	int saved_errno = errno;
+	va_list args;
+
+	ksft_cnt.ksft_xfail++;
+
+	va_start(args, msg);
+	printf("ok %d # XFAIL ", ksft_test_num());
+	errno = saved_errno;
+	vprintf(msg, args);
+	va_end(args);
+}
+
 static inline void ksft_test_result_skip(const char *msg, ...)
 {
 	int saved_errno = errno;
@@ -134,6 +191,7 @@ static inline void ksft_test_result_skip(const char *msg, ...)
 	va_end(args);
 }
 
+/* TODO: how does "error" differ from "fail" or "skip"? */
 static inline void ksft_test_result_error(const char *msg, ...)
 {
 	int saved_errno = errno;
@@ -156,11 +214,22 @@ static inline int ksft_exit_pass(void)
 
 static inline int ksft_exit_fail(void)
 {
-	printf("Bail out!\n");
 	ksft_print_cnts();
 	exit(KSFT_FAIL);
 }
 
+/**
+ * ksft_exit() - Exit selftest based on truth of condition
+ *
+ * @condition: if true, exit self test with success, otherwise fail.
+ */
+#define ksft_exit(condition) do {	\
+	if (!!(condition))		\
+		ksft_exit_pass();	\
+	else				\
+		ksft_exit_fail();	\
+	} while (0)
+
 static inline int ksft_exit_fail_msg(const char *msg, ...)
 {
 	int saved_errno = errno;