testsuite: ztest: Add logs flushing after each test case

When deferred mode is used, logging is using lowest priority
thread to process the logs. When test cases are performed one
by one processor never reaches lowest priority thread until
whole suite is completed. Added flushing after each test case.

Feature is optional (by default enabled).
CONFIG_TEST_LOGGING_FLUSH_AFTER_TEST=n to disable.

Signed-off-by: Krzysztof Chruscinski <[email protected]>

Author: nordic-krch

subsys/testsuite/Kconfig

@@ -87,6 +87,11 @@ config TEST_LOGGING_DEFAULTS
 	  logging configuration, or no logging at all, disable this
 	  in the project-level defconfig.
 
+config TEST_LOGGING_FLUSH_AFTER_TEST
+	bool "When enabled logs are flushed after each test case"
+	default y
+	depends on MULTITHREADING
+
 config TEST_ENABLE_USERSPACE
 	bool
 	depends on TEST_USERSPACE

subsys/testsuite/ztest/src/ztest.c

@@ -11,6 +11,7 @@
 #include <sys/libc-hooks.h>
 #endif
 #include <sys/reboot.h>
+#include <logging/log_ctrl.h>
 
 #ifdef KERNEL
 static struct k_thread ztest_thread;
@@ -368,15 +369,22 @@ static int run_test(struct unit_test *test)
 		}
 		k_thread_start(&ztest_thread);
 		k_thread_join(&ztest_thread, K_FOREVER);
+
 	} else {
 		test_result = 1;
 		run_test_functions(test);
 	}
 
+
 	phase = TEST_PHASE_TEARDOWN;
 	test->teardown();
 	phase = TEST_PHASE_FRAMEWORK;
 
+	/* Flush all logs in case deferred mode is used. */
+	while (IS_ENABLED(CONFIG_TEST_LOGGING_FLUSH_AFTER_TEST) && log_data_pending()) {
+		k_msleep(100);
+	}
+
 	if (test_result == -1) {
 		ret = TC_FAIL;
 	}