diff --git a/tests/test_ota_metadata/test_legacy/__init__.py b/tests/test_ota_metadata/test_legacy/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/test_ota_metadata/test_legacy/test_csv_parser.py b/tests/test_ota_metadata/test_legacy/test_csv_parser.py
new file mode 100644
index 000000000..e7b55282e
--- /dev/null
+++ b/tests/test_ota_metadata/test_legacy/test_csv_parser.py
@@ -0,0 +1,177 @@
+# Copyright 2022 TIER IV, INC. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+NOTE: the test cases are mostly re-used from the previous implementation.
+"""
+
+
+from __future__ import annotations
+
+import stat
+
+import pytest
+
+from ota_metadata.file_table import (
+    FileEntryAttrs,
+    FileTableDirectories,
+    FileTableNonRegularFiles,
+    FileTableRegularFiles,
+)
+from ota_metadata.legacy.csv_parser import (
+    parse_dirs_csv_line,
+    parse_persists_csv_line,
+    parse_regulars_csv_line,
+    parse_symlinks_csv_line,
+)
+from ota_metadata.legacy.rs_table import ResourceTable
+
+
+# try to include as any special characters as possible
+@pytest.mark.parametrize(
+    "_input, _ft_expected, _rs_expected",
+    (
+        # rev4: mode,uid,gid,link number,sha256sum,'path/to/file'[,size[,inode,[compression_alg]]]
+        (
+            r"0644,1000,1000,3,0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef,'/aaa\,'\'',Ελληνικό/to/file',1234,12345678,zst",
+            FileTableRegularFiles(
+                path=r"/aaa\,',Ελληνικό/to/file",
+                digest=bytes.fromhex(
+                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+                ),
+                entry_attrs=FileEntryAttrs(
+                    mode=int("0644", 8) | stat.S_IFREG,
+                    uid=1000,
+                    gid=1000,
+                    size=1234,
+                    inode=12345678,
+                ),
+            ),
+            ResourceTable(
+                digest=bytes.fromhex(
+                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+                ),
+                original_size=1234,
+                compression_alg="zst",
+            ),
+        ),
+        # rev3: mode,uid,gid,link number,sha256sum,'path/to/file'[,size[,inode]]
+        (
+            r"0644,1000,1000,3,0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef,'/aaa\,'\'',Ελληνικό/to/file',1234,12345678,",
+            FileTableRegularFiles(
+                path=r"/aaa\,',Ελληνικό/to/file",
+                digest=bytes.fromhex(
+                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+                ),
+                entry_attrs=FileEntryAttrs(
+                    mode=int("0644", 8) | stat.S_IFREG,
+                    uid=1000,
+                    gid=1000,
+                    size=1234,
+                    inode=12345678,
+                ),
+            ),
+            ResourceTable(
+                path=r"/aaa\,',Ελληνικό/to/file",
+                digest=bytes.fromhex(
+                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+                ),
+                original_size=1234,
+            ),
+        ),
+        # rev2: mode,uid,gid,link number,sha256sum,'path/to/file'[,size]
+        (
+            r"0644,1000,1000,1,0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef,'/aaa,'\'',Ελληνικό/to/file',1234",
+            FileTableRegularFiles(
+                path=r"/aaa,',Ελληνικό/to/file",
+                digest=bytes.fromhex(
+                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+                ),
+                entry_attrs=FileEntryAttrs(
+                    mode=int("0644", 8) | stat.S_IFREG,
+                    uid=1000,
+                    gid=1000,
+                    size=1234,
+                ),
+            ),
+            ResourceTable(
+                path=r"/aaa,',Ελληνικό/to/file",
+                digest=bytes.fromhex(
+                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+                ),
+                original_size=1234,
+            ),
+        ),
+        # rev1: mode,uid,gid,link number,sha256sum,'path/to/file'
+        # NOTE: rev1 is not supported anymore, the size field is MUST now.
+    ),
+)
+def test_regulars_txt(
+    _input: str, _ft_expected: FileTableRegularFiles, _rs_expected: ResourceTable
+):
+    _ft, _rs = parse_regulars_csv_line(_input)
+    assert _ft == _ft_expected
+    assert _rs == _rs_expected
+
+
+@pytest.mark.parametrize(
+    "_input, _expected",
+    (
+        (
+            r"0755,0,0,'/usr/lib/python3/aaa,'\''Ελληνικό'",
+            FileTableDirectories(
+                path=r"/usr/lib/python3/aaa,'Ελληνικό",
+                entry_attrs=FileEntryAttrs(
+                    mode=int("0755", 8) | stat.S_IFDIR, uid=0, gid=0
+                ),
+            ),
+        ),
+    ),
+)
+def test_dirs_txt(_input: str, _expected: FileTableDirectories):
+    assert parse_dirs_csv_line(_input) == _expected
+
+
+@pytest.mark.parametrize(
+    "_input, _expected",
+    (
+        # ensure ' are escaped and (,') will not break path parsing
+        (
+            r"0777,0,0,'/var/lib/ieee-data/iab.csv','../../ieee-data/'\'','\''Ελληνικό.csv'",
+            FileTableNonRegularFiles(
+                path=r"/var/lib/ieee-data/iab.csv",
+                entry_attrs=FileEntryAttrs(
+                    mode=int("0777", 8) | stat.S_IFLNK,
+                    uid=0,
+                    gid=0,
+                ),
+                contents=r"../../ieee-data/','Ελληνικό.csv".encode(),
+            ),
+        ),
+    ),
+)
+def test_symlinks_txt(_input: str, _expected: FileTableNonRegularFiles):
+    assert parse_symlinks_csv_line(_input) == _expected
+
+
+@pytest.mark.parametrize(
+    "_input, _expected",
+    (
+        (
+            r"'/etc/net'\''plan'",
+            r"/etc/net'plan",
+        ),
+    ),
+)
+def test_persistent_txt(_input: str, _expected: str):
+    assert parse_persists_csv_line(_input) == _expected
diff --git a/tests/test_ota_metadata/test_legacy.py b/tests/test_ota_metadata/test_legacy/test_legacy.py
similarity index 100%
rename from tests/test_ota_metadata/test_legacy.py
rename to tests/test_ota_metadata/test_legacy/test_legacy.py