feat: 添加 NapCat 适配器的入站消息编解码功能，增强插件配置更新逻辑和数据库交互测试

pytests/test_napcat_adapter_plugin.py

@@ -0,0 +1,60 @@
+"""NapCat 插件入口行为测试。"""
+
+from pathlib import Path
+from typing import List
+from types import SimpleNamespace
+
+import importlib
+import sys
+
+import pytest
+
+
+BUILT_IN_PLUGIN_ROOT = Path(__file__).resolve().parents[1] / "src" / "plugins" / "built_in"
+if str(BUILT_IN_PLUGIN_ROOT) not in sys.path:
+    sys.path.insert(0, str(BUILT_IN_PLUGIN_ROOT))
+
+NapCatAdapterPlugin = importlib.import_module("napcat_adapter.plugin").NapCatAdapterPlugin
+
+
+class DummyLogger:
+    """用于测试的轻量日志对象。"""
+
+    def __init__(self) -> None:
+        """初始化测试日志对象。"""
+        self.debug_messages: List[str] = []
+
+    def debug(self, message: str) -> None:
+        """记录调试日志。
+
+        Args:
+            message: 待记录的日志内容。
+        """
+        self.debug_messages.append(message)
+
+
+@pytest.mark.asyncio
+async def test_on_config_update_refreshes_settings_and_restarts(monkeypatch: pytest.MonkeyPatch) -> None:
+    """配置更新时应刷新插件配置、清空旧 settings，并触发连接重启。"""
+    plugin = NapCatAdapterPlugin()
+    plugin._ctx = SimpleNamespace(logger=DummyLogger())
+    plugin._settings = object()
+
+    restart_calls: List[dict] = []
+
+    async def fake_restart() -> None:
+        """记录一次重启调用。"""
+        restart_calls.append(dict(plugin._plugin_config))
+
+    monkeypatch.setattr(plugin, "_restart_connection_if_needed", fake_restart)
+
+    new_config = {
+        "plugin": {"enabled": True, "config_version": "0.1.0"},
+        "napcat_server": {"host": "127.0.0.1", "port": 3001},
+    }
+    await plugin.on_config_update(new_config, "v2")
+
+    assert plugin._plugin_config == new_config
+    assert plugin._settings is None
+    assert restart_calls == [new_config]
+    assert plugin.ctx.logger.debug_messages == ["NapCat 适配器收到配置更新通知: v2"]