diff --git a/tests/subsys/fs/fs_api/prj.conf b/tests/subsys/fs/fs_api/prj.conf
index 47eb9e2362c5..d5feeed8bffa 100644
--- a/tests/subsys/fs/fs_api/prj.conf
+++ b/tests/subsys/fs/fs_api/prj.conf
@@ -1,2 +1,3 @@
 CONFIG_FILE_SYSTEM=y
 CONFIG_ZTEST=y
+CONFIG_ZTEST_NEW_API=y
diff --git a/tests/subsys/fs/fs_api/src/main.c b/tests/subsys/fs/fs_api/src/main.c
deleted file mode 100644
index 0e768fac694d..000000000000
--- a/tests/subsys/fs/fs_api/src/main.c
+++ /dev/null
@@ -1,99 +0,0 @@
-/*
- * Copyright (c) 2016 Intel Corporation.
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
-#include "test_fs.h"
-
-/**
- * @brief Test file system interface implemented in kernel
- *
- * @defgroup filesystem File System
- *
- * @ingroup all_test
- * @{
- * @}
- */
-
-static void fs_setup(void)
-{
-	fs_register(TEST_FS_1, &temp_fs);
-}
-
-static void dummy_teardown(void)
-{
-	return;
-}
-
-static void dummy_setup(void)
-{
-	return;
-}
-
-static void fs_teardown(void)
-{
-	fs_unregister(TEST_FS_1, &temp_fs);
-}
-
-/**
- * @brief Common file system operations through a general interface
- *
- * @details After register file system:
- *            - mount
- *            - statvfs
- *            - mkdir
- *            - opendir
- *            - readdir
- *            - closedir
- *            - open
- *            - write
- *            - read
- *            - lseek
- *            - tell
- *            - truncate
- *            - sync
- *            - close
- *            - rename
- *            - stat
- *            - unlink
- *            - unmount
- *            - unregister file system
- *          the order of test cases is critical, one case depend on the
- *          case before it.
- *
- * @ingroup filesystem
- *
- */
-void test_main(void)
-{
-	ztest_test_suite(fat_fs_basic_test,
-			 ztest_unit_test(test_fs_register),
-			 ztest_unit_test_setup_teardown(test_mount,
-							fs_setup,
-							dummy_teardown),
-			 ztest_unit_test(test_fs_file_t_init),
-			 ztest_unit_test(test_fs_dir_t_init),
-			 ztest_unit_test(test_file_statvfs),
-			 ztest_unit_test(test_mkdir),
-			 ztest_unit_test(test_opendir),
-			 ztest_unit_test(test_closedir),
-			 ztest_unit_test(test_opendir_closedir),
-			 ztest_unit_test(test_lsdir),
-			 ztest_unit_test(test_file_open),
-			 ztest_unit_test(test_file_write),
-			 ztest_unit_test(test_file_read),
-			 ztest_unit_test(test_file_seek),
-			 ztest_unit_test(test_file_truncate),
-			 ztest_unit_test(test_file_close),
-			 ztest_unit_test(test_file_sync),
-			 ztest_unit_test(test_file_rename),
-			 ztest_unit_test(test_file_stat),
-			 ztest_unit_test(test_file_unlink),
-			 ztest_unit_test(test_unmount),
-			 ztest_unit_test_setup_teardown(test_mount_flags,
-							dummy_setup,
-							fs_teardown)
-			 );
-	ztest_run_test_suite(fat_fs_basic_test);
-}
diff --git a/tests/subsys/fs/fs_api/src/test_fs.h b/tests/subsys/fs/fs_api/src/test_fs.h
index 235e224abcd1..2b1ab08a6fff 100644
--- a/tests/subsys/fs/fs_api/src/test_fs.h
+++ b/tests/subsys/fs/fs_api/src/test_fs.h
@@ -33,27 +33,4 @@ struct test_fs_data {
 };
 
 void mock_opendir_result(int ret);
-
-void test_opendir_closedir(void);
-void test_fs_dir_t_init(void);
-void test_fs_file_t_init(void);
-void test_fs_register(void);
-void test_mount(void);
-void test_file_statvfs(void);
-void test_mkdir(void);
-void test_opendir(void);
-void test_closedir(void);
-void test_lsdir(void);
-void test_file_open(void);
-void test_file_write(void);
-void test_file_read(void);
-void test_file_seek(void);
-void test_file_truncate(void);
-void test_file_close(void);
-void test_file_sync(void);
-void test_file_rename(void);
-void test_file_stat(void);
-void test_file_unlink(void);
-void test_unmount(void);
-void test_mount_flags(void);
 #endif
diff --git a/tests/subsys/fs/fs_api/src/test_fs_dir_file.c b/tests/subsys/fs/fs_api/src/test_fs_dir_file.c
index f08daa13f6b4..0b7798b6e707 100644
--- a/tests/subsys/fs/fs_api/src/test_fs_dir_file.c
+++ b/tests/subsys/fs/fs_api/src/test_fs_dir_file.c
@@ -81,7 +81,7 @@ static const char test_str[] = "hello world!";
 /**
  * @brief Test fs_file_t_init initializer
  */
-void test_fs_file_t_init(void)
+ZTEST(fs_api_dir_file, test_fs_file_t_init)
 {
 	struct fs_file_t fst;
 
@@ -96,7 +96,7 @@ void test_fs_file_t_init(void)
 /**
  * @brief Test fs_dir_t_init initializer
  */
-void test_fs_dir_t_init(void)
+ZTEST(fs_api_dir_file, test_fs_dir_t_init)
 {
 	struct fs_dir_t dirp;
 
@@ -149,6 +149,7 @@ void test_mount(void)
 	zassert_not_equal(ret, 0, "Mount to a mounted dir");
 
 	fs_unregister(TEST_FS_2, &temp_fs);
+	memset(&null_fs, 0, sizeof(null_fs));
 	fs_register(TEST_FS_2, &null_fs);
 
 	TC_PRINT("Mount a file system has no interface implemented\n");
@@ -191,6 +192,10 @@ void test_unmount(void)
 	TC_PRINT("unmount a file system has no unmount functionality\n");
 	ret = fs_unmount(&test_fs_mnt_no_op);
 	zassert_not_equal(ret, 0, "Unmount a fs has no unmount functionality");
+	/* assign a unmount interface to null_fs to unmount it */
+	null_fs.unmount = temp_fs.unmount;
+	ret = fs_unmount(&test_fs_mnt_no_op);
+	zassert_equal(ret, 0, "file system should be unmounted");
 	/* TEST_FS_2 is registered in test_mount(), unregister it here */
 	fs_unregister(TEST_FS_2, &null_fs);
 }
@@ -200,7 +205,7 @@ void test_unmount(void)
  *
  * @ingroup filesystem_api
  */
-void test_file_statvfs(void)
+ZTEST(fs_api_dir_file, test_file_statvfs)
 {
 	struct fs_statvfs stat;
 	int ret;
@@ -640,7 +645,7 @@ static int _test_file_sync(void)
  *
  * @ingroup filesystem_api
  */
-void test_file_sync(void)
+ZTEST(fs_api_dir_file, test_file_sync)
 {
 	zassert_true(_test_file_sync() == TC_PASS, NULL);
 }
@@ -910,7 +915,7 @@ void test_file_close(void)
  *
  * @ingroup filesystem_api
  */
-void test_file_rename(void)
+ZTEST(fs_api_dir_file, test_file_rename)
 {
 	int ret = TC_FAIL;
 
@@ -955,7 +960,7 @@ void test_file_rename(void)
  *
  * @ingroup filesystem_api
  */
-void test_file_stat(void)
+ZTEST(fs_api_dir_file, test_file_stat)
 {
 	int ret;
 	struct fs_dirent entry;
@@ -992,7 +997,7 @@ void test_file_stat(void)
  *
  * @ingroup filesystem_api
  */
-void test_file_unlink(void)
+ZTEST(fs_api_dir_file, test_file_unlink)
 {
 	int ret;
 
@@ -1031,3 +1036,53 @@ void test_file_unlink(void)
 
 	TC_PRINT("File (%s) deleted successfully!\n", TEST_FILE_RN);
 }
+
+static void *fs_api_setup(void)
+{
+	fs_register(TEST_FS_1, &temp_fs);
+	fs_mount(&test_fs_mnt_1);
+	memset(&null_fs, 0, sizeof(null_fs));
+	null_fs.mount = temp_fs.mount;
+	null_fs.unmount = temp_fs.unmount;
+	fs_register(TEST_FS_2, &null_fs);
+	fs_mount(&test_fs_mnt_no_op);
+	return NULL;
+}
+
+static void fs_api_teardown(void *fixtrue)
+{
+	fs_unmount(&test_fs_mnt_no_op);
+	fs_unregister(TEST_FS_2, &null_fs);
+	fs_unmount(&test_fs_mnt_1);
+	fs_unregister(TEST_FS_1, &temp_fs);
+}
+
+ZTEST(fs_api_dir_file, test_fs_dir)
+{
+	test_mkdir();
+	test_opendir();
+	test_closedir();
+	test_opendir_closedir();
+	test_lsdir();
+}
+
+ZTEST(fs_api_dir_file, test_file_ops)
+{
+	test_file_open();
+	test_file_write();
+	test_file_read();
+	test_file_seek();
+	test_file_truncate();
+	test_file_close();
+}
+
+ZTEST(fs_api_register_mount, test_mount_unmount)
+{
+	fs_register(TEST_FS_1, &temp_fs);
+	test_mount();
+	test_unmount();
+	fs_unregister(TEST_FS_1, &temp_fs);
+}
+
+ZTEST_SUITE(fs_api_register_mount, NULL, NULL, NULL, NULL, NULL);
+ZTEST_SUITE(fs_api_dir_file, NULL, fs_api_setup, NULL, NULL, fs_api_teardown);
diff --git a/tests/subsys/fs/fs_api/src/test_multi_fs.c b/tests/subsys/fs/fs_api/src/test_multi_fs.c
index 8c7594c707db..a0a72b36e60a 100644
--- a/tests/subsys/fs/fs_api/src/test_multi_fs.c
+++ b/tests/subsys/fs/fs_api/src/test_multi_fs.c
@@ -123,7 +123,7 @@ static int test_fs_external(void)
  *@{
  */
 
-void test_fs_register(void)
+ZTEST(fs_api_register_mount, test_fs_register)
 {
 	zassert_true(test_fs_init() == 0, "Failed to register filesystems");
 	zassert_true(test_fs_readmount() == 0, "Failed to readmount");