diff --git a/tests/backend/constants.py b/tests/backend/constants.py
new file mode 100644
index 00000000..a4feef51
--- /dev/null
+++ b/tests/backend/constants.py
@@ -0,0 +1,22 @@
+#
+# Copyright (C) 2024 Satoru SATOH <satoru.satoh gmail.com>
+# SPDX-License-Identifier: MIT
+#
+# pylint: disable=missing-docstring
+"""Constants for tests.backend.*."""
+from __future__ import annotations
+
+import pathlib
+
+from . import common as TT
+
+
+CURDIR: pathlib.Path = pathlib.Path(__file__).parent
+
+MOD_TYPE: str = "json"
+MOD_BACKEND: str = "stdlib"
+
+TEST_FILE = (
+    CURDIR / "loaders" / MOD_TYPE / f"test_{MOD_TYPE}_{MOD_BACKEND}.py"
+)
+TEST_DATADIR = TT.common.RESOURCE_DIR / "loaders" / "json.stdlib"
diff --git a/tests/backend/test_common.py b/tests/backend/test_common.py
index e687d667..a638f10e 100644
--- a/tests/backend/test_common.py
+++ b/tests/backend/test_common.py
@@ -6,24 +6,19 @@
 r"""Test cases for Test Data Collecor."""
 from __future__ import annotations
 
-import pathlib
-
 import pytest
 
 import anyconfig.backend.json.stdlib as MOD
 
 from . import common as TT
-
-
-CURDIR: pathlib.Path = pathlib.Path(__file__).parent
-TESTFILE = CURDIR / "loaders" / "json" / "test_json_stdlib.py"
-
-TEST_DATADIR = TT.common.RESOURCE_DIR / "loaders" / "json.stdlib"
+from .constants import (
+    MOD_BACKEND, MOD_TYPE, TEST_FILE, TEST_DATADIR
+)
 
 
 @pytest.mark.parametrize(
     ("testfile", "exp"),
-    ((str(TESTFILE), "json.stdlib"),
+    ((str(TEST_FILE), f"{MOD_TYPE}.{MOD_BACKEND}"),
      (__file__, NameError),
      ),
 )
@@ -37,7 +32,7 @@ def test_get_name(testfile, exp):
 
 @pytest.mark.parametrize(
     ("testfile", "exp"),
-    ((str(TESTFILE), MOD),
+    ((str(TEST_FILE), MOD),
      ),
 )
 def test_get_mod(testfile, exp):
@@ -46,7 +41,7 @@ def test_get_mod(testfile, exp):
 
 @pytest.mark.parametrize(
     ("path", "exp"),
-    ((str(TESTFILE), TEST_DATADIR),
+    ((str(TEST_FILE), TEST_DATADIR),
      ),
 )
 def test_get_test_resdir(path, exp):