diff --git a/src/core/log_default.c b/src/core/log_default.c
index 8728c51f91e..b761a85a49a 100644
--- a/src/core/log_default.c
+++ b/src/core/log_default.c
@@ -93,7 +93,7 @@ get_timestamp_prefix(char *buf, size_t buf_size)
  * are formatted and inserted in the message.
  *
  * ASSUMPTIONS:
- * - level >= CORE_LOG_LEVEL_FATAL && level <= CORE_LOG_LEVEL_DEBUG
+ * - level >= CORE_LOG_LEVEL_HARK && level <= CORE_LOG_LEVEL_DEBUG
  * - level <= Core_log_threshold[LOG_THRESHOLD]
  * - file == NULL || (file != NULL && function != NULL)
  */
diff --git a/src/test/Makefile b/src/test/Makefile
index 748d9fd6259..e39efaaa792 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -23,7 +23,6 @@ OBJ_TESTS = \
 	obj_many_size_allocs\
 	obj_realloc\
 	obj_sync\
-	\
 	obj_action\
 	obj_alloc\
 	obj_badblock\
@@ -109,6 +108,7 @@ OBJ_TESTS = \
 OTHER_TESTS = \
 	arch_flags\
 	core_log_internal\
+	core_log_default_function\
 	core_log_max\
 	checksum\
 	compat_incompat_features\
diff --git a/src/test/core_log_default_function/.gitignore b/src/test/core_log_default_function/.gitignore
new file mode 100644
index 00000000000..5c484fc37a8
--- /dev/null
+++ b/src/test/core_log_default_function/.gitignore
@@ -0,0 +1 @@
+core_log_default_function
diff --git a/src/test/core_log_default_function/Makefile b/src/test/core_log_default_function/Makefile
new file mode 100644
index 00000000000..f2cbfd86669
--- /dev/null
+++ b/src/test/core_log_default_function/Makefile
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright 2024, Intel Corporation
+
+TARGET = core_log_default_function
+OBJS = core_log_default_function.o
+
+BUILD_STATIC_DEBUG=n
+BUILD_STATIC_NONDEBUG=n
+
+LIBPMEMCORE=internal-debug
+
+include ../Makefile.inc
+LDFLAGS += $(call extract_funcs, core_log_default_function.c)
diff --git a/src/test/core_log_default_function/TESTS.py b/src/test/core_log_default_function/TESTS.py
new file mode 100755
index 00000000000..31b588cba11
--- /dev/null
+++ b/src/test/core_log_default_function/TESTS.py
@@ -0,0 +1,36 @@
+#!../env.py
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright 2024, Intel Corporation
+#
+
+
+import testframework as t
+from testframework import granularity as g
+
+
+@g.require_granularity(g.ANY)
+class CORE_LOG(t.BaseTest):
+    test_type = t.Short
+
+    def run(self, ctx):
+        ctx.exec('core_log_default_function', self.test_case)
+
+
+class TEST0(CORE_LOG):
+    test_case = 'test_default_function'
+
+
+class TEST1(CORE_LOG):
+    test_case = 'test_default_function_bad_file_name'
+
+
+class TEST2(CORE_LOG):
+    test_case = 'test_default_function_short_file_name'
+
+
+class TEST3(CORE_LOG):
+    test_case = 'test_default_function_no_file_name'
+
+
+class TEST4(CORE_LOG):
+    test_case = 'test_default_function_bad_timestamp'
diff --git a/src/test/core_log_default_function/core_log_default_function.c b/src/test/core_log_default_function/core_log_default_function.c
new file mode 100644
index 00000000000..29f5a693788
--- /dev/null
+++ b/src/test/core_log_default_function/core_log_default_function.c
@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/* Copyright 2024, Intel Corporation */
+
+/*
+ * core_log_default_function.c -- unit test for core_log_default_function
+ */
+
+#undef _GNU_SOURCE
+#include <string.h>
+#include <syslog.h>
+
+#include "unittest.h"
+#include "log_internal.h"
+#include "log_default.h"
+
+#define NO_ARGS_CONSUMED 0
+
+#define MESSAGE "Test message"
+#define TIMESTAMP "DUMMY TIMESTAMP"
+#define FILE_NAME "dummy.c"
+#define FILE_NAME_W_PATH "dummy_path/dummy_path/" FILE_NAME
+#define FILE_INFO_ERROR "[file info error]: "
+#define FUNCTION_NAME "dummy_func()"
+#define FILE_INFO FILE_NAME ": 123: " FUNCTION_NAME ": "
+#define LINE_NO 1357
+
+static const char log_level_names[CORE_LOG_LEVEL_MAX][9] = {
+	[CORE_LOG_LEVEL_HARK]		= "*HARK*  ",
+	[CORE_LOG_LEVEL_FATAL]		= "*FATAL* ",
+	[CORE_LOG_LEVEL_ERROR]		= "*ERROR* ",
+	[CORE_LOG_LEVEL_WARNING]	= "*WARN*  ",
+	[CORE_LOG_LEVEL_NOTICE]		= "*NOTE*  ",
+	[CORE_LOG_LEVEL_INFO]		= "*INFO*  ",
+	[CORE_LOG_LEVEL_DEBUG]		= "*DEBUG* ",
+};
+
+static const int log_level_syslog_severity[] = {
+	[CORE_LOG_LEVEL_HARK]		= LOG_NOTICE,
+	[CORE_LOG_LEVEL_FATAL]		= LOG_CRIT,
+	[CORE_LOG_LEVEL_ERROR]		= LOG_ERR,
+	[CORE_LOG_LEVEL_WARNING]	= LOG_WARNING,
+	[CORE_LOG_LEVEL_NOTICE]		= LOG_NOTICE,
+	[CORE_LOG_LEVEL_INFO]		= LOG_INFO,
+	[CORE_LOG_LEVEL_DEBUG]		= LOG_DEBUG,
+};
+
+const char *Log_level_name;
+const char *File_info;
+const char *Message;
+
+char *Strchr_ret;
+
+FUNC_MOCK(strrchr, char *, const char *__s, int __c)
+FUNC_MOCK_RUN_DEFAULT {
+	UT_ASSERTeq(__c, '/');
+	return Strchr_ret;
+}
+FUNC_MOCK_END
+
+static struct {
+	const char *file_name;
+	const char *function_name;
+	int force_error;
+	int ret;
+} Snprintf_context;
+
+FUNC_MOCK(snprintf, int, char *__restrict __s, size_t __maxlen,
+		const char *__restrict __format, ...)
+/* file info */
+	FUNC_MOCK_RUN(0) {
+/* second parameter after __format equal to -1 causes negative value return */
+		va_list arg;
+		va_start(arg, __format);
+		UT_ASSERTstreq(__format, "%s: %3d: %s: ");
+		char *file_name = va_arg(arg, char *);
+		UT_ASSERTstreq(file_name, Snprintf_context.file_name);
+		int line_no = va_arg(arg, int);
+		UT_ASSERTeq(line_no, LINE_NO);
+		char *function_name = va_arg(arg, char *);
+		UT_ASSERTstreq(function_name, Snprintf_context.function_name);
+		/* fill-in the given buffer to verify no memory overwritten */
+		memset(__s, 'x', __maxlen);
+		*(__s + __maxlen - 1) = '\0';
+		memcpy(__s, FILE_INFO, sizeof(FILE_INFO) + 1);
+		va_end(arg);
+		if (Snprintf_context.ret != 0)
+			return Snprintf_context.ret;
+		else
+			return __maxlen;
+	}
+/* get time prefix */
+	FUNC_MOCK_RUN(1) {
+		UT_ASSERTstreq(__format, "%s.%06ld ");
+		if (Snprintf_context.force_error) {
+		/* fill-in the given buffer to verify no memory overwritten */
+			memset(__s, 'x', __maxlen);
+		}
+		else
+			strncpy(__s, TIMESTAMP, __maxlen);
+		return __maxlen;
+	}
+FUNC_MOCK_RUN_DEFAULT {
+	UT_FATAL("Unexpected #%d sprintf: %s", RCOUNTER(snprintf), __format);
+}
+FUNC_MOCK_END
+
+static struct {
+	int no_of_calls;
+	int __pri;
+	char *file_info;
+} Syslog_context;
+
+FUNC_MOCK(syslog, void, int __pri, const char *__fmt, ...)
+FUNC_MOCK_RUN_DEFAULT {
+	Syslog_context.no_of_calls++;
+	UT_ASSERTeq(__pri, Syslog_context.__pri);
+	UT_ASSERTstreq(__fmt, "%s%s%s");
+	va_list arg;
+	va_start(arg, __fmt);
+	char *log_level_name = va_arg(arg, char *);
+	UT_ASSERTstreq(log_level_name, Log_level_name);
+	char *file_info = va_arg(arg, char *);
+	UT_ASSERTstreq(file_info, Syslog_context.file_info);
+	char *message = va_arg(arg, char *);
+	UT_ASSERTstreq(message, Message);
+	va_end(arg);
+}
+FUNC_MOCK_END
+
+static struct {
+	int no_of_calls;
+	char *times_stamp;
+	const char *file_info;
+} Fprintf_context;
+
+FUNC_MOCK(fprintf, int, FILE *__restrict __stream, const char *__restrict __fmt,
+	...)
+FUNC_MOCK_RUN_DEFAULT {
+	Fprintf_context.no_of_calls++;
+	UT_ASSERTeq(__stream, stderr);
+	va_list arg;
+	va_start(arg, __fmt);
+	char *times_tamp = va_arg(arg, char *);
+	UT_ASSERTstreq(times_tamp, Fprintf_context.times_stamp);
+	va_arg(arg, int); /* skip syscall(SYS_gettid) */
+	char *log_level_name = va_arg(arg, char *);
+	UT_ASSERTstreq(log_level_name, Log_level_name);
+	char *file_info = va_arg(arg, char *);
+	UT_ASSERTstreq(file_info, Syslog_context.file_info);
+	char *message = va_arg(arg, char *);
+	UT_ASSERTstreq(message, Message);
+	va_end(arg);
+	return 0;
+}
+FUNC_MOCK_END
+
+/* Testshelpers */
+#define TEST_SETUP(_MESSAGE) Message = _MESSAGE
+
+#define TEST_STEP_SETUP(_LEVEL, _FILE_NAME_SHORT, _FUNCTION_NAME) \
+	do { \
+		FUNC_MOCK_RCOUNTER_SET(snprintf, 0); \
+		Log_level_name = log_level_names[_LEVEL]; \
+		memset(&Syslog_context, 0, sizeof(Syslog_context)); \
+		Syslog_context.__pri = log_level_syslog_severity[_LEVEL]; \
+		Syslog_context.file_info = FILE_INFO; \
+		memset(&Snprintf_context, 0, sizeof(Snprintf_context)); \
+		Snprintf_context.file_name = _FILE_NAME_SHORT; \
+		Snprintf_context.function_name = _FUNCTION_NAME; \
+		memset(&Fprintf_context, 0, sizeof(Fprintf_context)); \
+		Fprintf_context.times_stamp = TIMESTAMP; \
+		Strchr_ret = "/"_FILE_NAME_SHORT; \
+	} while (0)
+
+#define TEST_STEP_CHECK(_FPRINTF_CALLED) \
+	do { \
+		UT_ASSERTeq(Syslog_context.no_of_calls, 1); \
+		UT_ASSERTeq(Fprintf_context.no_of_calls, _FPRINTF_CALLED); \
+	} while (0)
+
+/* basic test with a normal message pass through */
+static int
+test_default_function(const struct test_case *tc, int argc, char *argv[])
+{
+	TEST_SETUP(MESSAGE);
+	for (enum core_log_level treshold = CORE_LOG_LEVEL_HARK;
+		treshold < CORE_LOG_LEVEL_MAX; treshold++) {
+		core_log_set_threshold(CORE_LOG_THRESHOLD_AUX, treshold);
+		for (enum core_log_level level = CORE_LOG_LEVEL_HARK;
+			level < CORE_LOG_LEVEL_MAX; level++) {
+			TEST_STEP_SETUP(level, FILE_NAME, FUNCTION_NAME);
+			core_log_default_function(NULL, level, FILE_NAME_W_PATH,
+				LINE_NO, FUNCTION_NAME, MESSAGE);
+			if (level == CORE_LOG_LEVEL_HARK || level > treshold)
+				TEST_STEP_CHECK(0);
+			else
+				TEST_STEP_CHECK(1);
+		}
+	}
+
+	return NO_ARGS_CONSUMED;
+}
+
+/* test to check that information about a bad file is printed */
+static int
+test_default_function_bad_file_name(const struct test_case *tc, int argc,
+	char *argv[])
+{
+	core_log_set_threshold(CORE_LOG_THRESHOLD_AUX, CORE_LOG_LEVEL_DEBUG);
+	TEST_SETUP(MESSAGE);
+	TEST_STEP_SETUP(CORE_LOG_LEVEL_DEBUG, FILE_INFO_ERROR, FUNCTION_NAME);
+	Snprintf_context.ret = -1;
+	Syslog_context.file_info = FILE_INFO_ERROR;
+	core_log_default_function(NULL, CORE_LOG_LEVEL_DEBUG, FILE_NAME_W_PATH,
+		LINE_NO, FUNCTION_NAME, MESSAGE);
+	TEST_STEP_CHECK(1);
+
+	return NO_ARGS_CONSUMED;
+}
+
+/* test to check that short file name (w/o path) is properly printed */
+static int
+test_default_function_short_file_name(const struct test_case *tc, int argc,
+	char *argv[])
+{
+	core_log_set_threshold(CORE_LOG_THRESHOLD_AUX, CORE_LOG_LEVEL_DEBUG);
+	TEST_SETUP(MESSAGE);
+	TEST_STEP_SETUP(CORE_LOG_LEVEL_DEBUG, FILE_NAME, FUNCTION_NAME);
+	Strchr_ret = NULL;
+	core_log_default_function(NULL, CORE_LOG_LEVEL_DEBUG, FILE_NAME,
+		LINE_NO, FUNCTION_NAME, MESSAGE);
+	TEST_STEP_CHECK(1);
+
+	return NO_ARGS_CONSUMED;
+}
+
+/* test to check no fileinfo when filename is NULL */
+static int
+test_default_function_no_file_name(const struct test_case *tc, int argc,
+	char *argv[])
+{
+	core_log_set_threshold(CORE_LOG_THRESHOLD_AUX, CORE_LOG_LEVEL_DEBUG);
+	TEST_SETUP(MESSAGE);
+	TEST_STEP_SETUP(CORE_LOG_LEVEL_DEBUG, "", FUNCTION_NAME);
+	/* skip file_info snprintf() */
+	FUNC_MOCK_RCOUNTER_SET(snprintf, 1);
+	Syslog_context.file_info = "";
+	core_log_default_function(NULL, CORE_LOG_LEVEL_DEBUG, NULL,
+		LINE_NO, FUNCTION_NAME, MESSAGE);
+	TEST_STEP_CHECK(1);
+
+	return NO_ARGS_CONSUMED;
+}
+
+/* test to check timestamp error */
+static int
+test_default_function_bad_timestamp(const struct test_case *tc, int argc,
+	char *argv[])
+{
+	core_log_set_threshold(CORE_LOG_THRESHOLD_AUX, CORE_LOG_LEVEL_DEBUG);
+	TEST_SETUP(MESSAGE);
+	TEST_STEP_SETUP(CORE_LOG_LEVEL_DEBUG, FILE_NAME, FUNCTION_NAME);
+	Snprintf_context.force_error = 1; /* fail the file_info snprintf() */
+	Fprintf_context.times_stamp = "[time error] ";
+	core_log_default_function(NULL, CORE_LOG_LEVEL_DEBUG, FILE_NAME,
+		LINE_NO, FUNCTION_NAME, MESSAGE);
+	TEST_STEP_CHECK(1);
+
+	return NO_ARGS_CONSUMED;
+}
+
+static struct test_case test_cases[] = {
+	TEST_CASE(test_default_function),
+	TEST_CASE(test_default_function_bad_file_name),
+	TEST_CASE(test_default_function_short_file_name),
+	TEST_CASE(test_default_function_no_file_name),
+	TEST_CASE(test_default_function_bad_timestamp),
+};
+
+int
+main(int argc, char *argv[])
+{
+	START(argc, argv, "core_log_default_function");
+	TEST_CASE_PROCESS(argc, argv, test_cases, ARRAY_SIZE(test_cases));
+	DONE(NULL);
+}
diff --git a/src/test/core_log_internal/Makefile b/src/test/core_log_internal/Makefile
index 221ebfd1f7b..1fe8a911bd3 100644
--- a/src/test/core_log_internal/Makefile
+++ b/src/test/core_log_internal/Makefile
@@ -7,7 +7,9 @@ OBJS = core_log_internal.o
 BUILD_STATIC_DEBUG=n
 BUILD_STATIC_NONDEBUG=n
 
-# `internal` is required for proper mock integration
+# 'internal' is required for proper mock integration
+# 'nondebug' is required for proper execution of test_CORE_LOG_TRESHOLD_DEFAULT
+# (use nondebug version of core/log.o)
 LIBPMEMCORE=internal-nondebug
 
 include ../Makefile.inc