diff --git a/src/pyflowx/executors.py b/src/pyflowx/executors.py
index 7a6bf9f..5f61250 100644
--- a/src/pyflowx/executors.py
+++ b/src/pyflowx/executors.py
@@ -53,7 +53,7 @@ class Strategy(enum.Enum):
     ASYNC = "async"
 
 
-def _normalize_strategy(strategy: str | Strategy) -> Strategy:
+def normalize_strategy(strategy: str | Strategy) -> Strategy:
     """将字符串或 Strategy 归一化为 Strategy 枚举.
 
     Parameters
@@ -436,7 +436,7 @@ def run(
         任何任务耗尽重试后仍失败时。运行在失败层中止；后续层的任务
         不会被执行。
     """
-    normalized = _normalize_strategy(strategy)
+    normalized = normalize_strategy(strategy)
 
     graph.validate()
     layers = graph.layers()
diff --git a/src/pyflowx/runner.py b/src/pyflowx/runner.py
index 5223495..44c43d2 100644
--- a/src/pyflowx/runner.py
+++ b/src/pyflowx/runner.py
@@ -26,7 +26,7 @@ import sys
 from typing import Sequence
 
 from .errors import PyFlowXError
-from .executors import Strategy, _normalize_strategy, run
+from .executors import Strategy, normalize_strategy, run
 from .graph import Graph
 
 __all__ = ["CliExitCode", "CliRunner"]
@@ -132,7 +132,7 @@ class CliRunner:
                     f"CliRunner 命令 {name!r} 的值必须是 Graph 实例, 实际是 {type(graph).__name__}"
                 )
         self._graphs: dict[str, Graph] = dict(graphs)
-        self._strategy: Strategy = _normalize_strategy(strategy)
+        self._strategy: Strategy = normalize_strategy(strategy)
         self._description: str = description
         self._verbose: bool = verbose
 
diff --git a/tests/test_storage.py b/tests/test_storage.py
index 9506912..9a4e779 100644
--- a/tests/test_storage.py
+++ b/tests/test_storage.py
@@ -5,6 +5,7 @@ from __future__ import annotations
 import json
 import os
 import tempfile
+from pathlib import Path
 from typing import Any
 
 import pytest
@@ -13,6 +14,27 @@ from pyflowx.errors import StorageError
 from pyflowx.storage import JSONBackend, MemoryBackend, StateBackend, resolve_backend
 
 
+@pytest.fixture
+def mock_tmp_json(tmp_path: Path) -> Path:
+    """模拟临时 JSON 文件。"""
+    path = tmp_path / "state.json"
+    path.touch()
+    return path
+
+
+class TestStateBackend:
+    """测试状态后端。"""
+
+    def test_json_backend_save_and_load(self, mock_tmp_json: Path) -> None:
+        """测试 JSON 后端保存和加载。"""
+        b = JSONBackend(str(mock_tmp_json))
+        assert not b.has("a")
+        b.save("a", 1)
+        assert b.has("a")
+        assert b.get("a") == 1
+        assert dict(b.load()) == {"a": 1}
+
+
 # ---------------------------------------------------------------------- #
 # MemoryBackend
 # ---------------------------------------------------------------------- #
@@ -59,7 +81,7 @@ def test_json_backend_clear() -> None:
         b.clear()
         assert not b.has("a")
         # 文件应被写入空 dict
-        with open(path, "r", encoding="utf-8") as fh:
+        with open(path, encoding="utf-8") as fh:
             assert json.load(fh) == {}
 
 
@@ -123,7 +145,7 @@ def test_json_backend_flush_os_error(monkeypatch: pytest.MonkeyPatch) -> None:
         monkeypatch.setattr(os, "replace", original_replace)
 
 
-def test_json_backend_corrupt_file_raises() -> None:
+def test_json_backend_corrupt_file_raises(tmp_path: Path) -> None:
     """损坏的 JSON 文件应抛 StorageError。"""
     with tempfile.TemporaryDirectory() as tmp:
         path = os.path.join(tmp, "state.json")
@@ -133,14 +155,12 @@ def test_json_backend_corrupt_file_raises() -> None:
             JSONBackend(path)
 
 
-def test_json_backend_non_dict_content_ignored() -> None:
+def test_json_backend_non_dict_content_ignored(tmp_path: Path) -> None:
     """文件内容是合法 JSON 但非 dict 时应被忽略（保持空）。"""
-    with tempfile.TemporaryDirectory() as tmp:
-        path = os.path.join(tmp, "state.json")
-        with open(path, "w", encoding="utf-8") as fh:
-            json.dump([1, 2, 3], fh)  # list 而非 dict
-        b = JSONBackend(path)
-        assert dict(b.load()) == {}
+    path = tmp_path / "state.json"
+    _ = path.write_text(json.dumps([1, 2, 3]))  # list 而非 dict
+    b = JSONBackend(str(path))
+    assert dict(b.load()) == {}
 
 
 # ---------------------------------------------------------------------- #