test(unittests): Add an automatic fixture for test environment variable isolation

- Added an `autouse` fixture to automatically clean up environment variables related to the SDK configuration.
- Prevents local `.env` files from interfering with the environment variable settings used in unit tests.
- Cleans up specific environment variables to prevent assertion failures within `respx` mocks.
- Ensures environment variable isolation between test cases, thereby enhancing test stability.
- Cleans up only those environment variables that the SDK reads by default, without affecting user-defined variables.

Signed-off-by: 寒光 <2510399607@qq.com>

Author: TJKkking

tests/unittests/conftest.py

@@ -0,0 +1,54 @@
+"""Unit test fixtures / 单元测试公共 fixture.
+
+本模块统一为 tests/unittests/ 目录提供测试隔离保障。
+
+Why:
+    agentrun.utils.config 在模块导入时调用 load_dotenv(), 会把仓库根目录
+    的 .env 注入到 os.environ。Config() 在构造时会用 get_env_with_default
+    读取这些环境变量作为默认值, 导致：
+      - respx mock 的 URL 是基于 SDK 默认 account_id / region 构造,
+        而实际请求打到开发者本地 .env 里的真实 account / region,
+        触发 "AllMockedAssertionError: ... not mocked!"
+      - 硬编码期望默认 account_id / region 的断言直接 AssertionError
+
+How:
+    autouse fixture 在每个 test 进入前, 通过 monkeypatch.delenv 清理
+    Config.__init__ 读取的那一组 env。monkeypatch 会在 test 结束时
+    自动恢复原值, 不影响仓库 .env 文件本身, 也不影响显式使用
+    patch.dict(os.environ, ...) 设置 test 用凭据的测试 (patch.dict
+    会覆盖 delenv 的结果)。
+"""
+
+from typing import List
+
+import pytest
+
+# Config.__init__ 默认值会读取的环境变量白名单
+# 仅清理这些 key, 不动用户测试自己 set 的其他 AGENTRUN_* 变量
+# (例如 memory_collection test 里的 AGENTRUN_MYSQL_PUBLIC_HOST)
+_SDK_CONFIG_ENV_KEYS: List[str] = [
+    # 凭据类 / Credentials
+    "AGENTRUN_ACCESS_KEY_ID",
+    "ALIBABA_CLOUD_ACCESS_KEY_ID",
+    "AGENTRUN_ACCESS_KEY_SECRET",
+    "ALIBABA_CLOUD_ACCESS_KEY_SECRET",
+    "AGENTRUN_SECURITY_TOKEN",
+    "ALIBABA_CLOUD_SECURITY_TOKEN",
+    # 账号与区域 / Account & Region
+    "AGENTRUN_ACCOUNT_ID",
+    "FC_ACCOUNT_ID",
+    "AGENTRUN_REGION",
+    "FC_REGION",
+    # Endpoint 类 / Endpoints
+    "AGENTRUN_CONTROL_ENDPOINT",
+    "AGENTRUN_DATA_ENDPOINT",
+    "DEVS_ENDPOINT",
+    "BAILIAN_ENDPOINT",
+]
+
+
+@pytest.fixture(autouse=True)
+def _isolate_sdk_config_env(monkeypatch: pytest.MonkeyPatch) -> None:
+    """自动为每个 unit test 清理 SDK Config 相关 env, 避免被本地 .env 污染."""
+    for key in _SDK_CONFIG_ENV_KEYS:
+        monkeypatch.delenv(key, raising=False)