unit-tests: Add ability to issue a warning message for a test case

This way we can warn if we e.g. skipped actually doing something due to
dependencies (otherwise the test case would just appear to have succeeded).

src/libstrongswan/tests/test_suite.h

@@ -219,6 +219,17 @@ void test_setup_timeout(int s);
  */
 int test_failure_get(char *msg, int len, const char **file);
 
+/**
+ * Get info about a warning if one was issued during the test. Resets the
+ * warning state.
+ *
+ * @param msg		buffer receiving warning
+ * @param len		size of msg buffer
+ * @param file		pointer receiving source code file
+ * @return			source code line number, 0 if no warning issued
+ */
+int test_warning_get(char *msg, int len, const char **file);
+
 /**
  * Get a backtrace for a failure.
  *
@@ -246,6 +257,18 @@ void test_fail_vmsg(const char *file, int line, char *fmt, va_list args);
  */
 void test_fail_msg(const char *file, int line, char *fmt, ...);
 
+/**
+ * Issue a warning for a particular test with a message using printf style
+ * arguments. This does not fail the test, and only the last warning for each
+ * test is kept.
+ *
+ * @param file		source code file name
+ * @param line		source code line number
+ * @param fmt		printf format string
+ * @param ...		arguments for fmt
+ */
+void test_warn_msg(const char *file, int line, char *fmt, ...);
+
 /**
  * Let a test fail if one of the worker threads has failed (only if called from
  * the main thread).
@@ -345,6 +368,7 @@ void test_fail_if_worker_failed();
 #define ck_assert_msg test_assert_msg
 #define ck_assert_str_eq test_str_eq
 #define ck_assert_chunk_eq test_chunk_eq
+#define warn(fmt, ...) test_warn_msg(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
 #define fail(fmt, ...) test_fail_msg(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
 #define fail_if(x, fmt, ...) \
 ({ \