fix(onebot): get_group_files_by_folder 不再丢弃子文件夹 (#2095)

该接口的 returnSchema 声明了 folders（文件夹列表），actionDescription
也写着「获取指定群文件夹下的文件及子文件夹列表」，但 _handle 把 folders
硬编码成空数组。

它调用的 MsgApi.getGroupFileList 与 get_group_root_files 相同，返回项
既可能带 fileInfo 也可能带 folderInfo；兄弟实现 GetGroupRootFiles 把
两类都映射了出来。后果是进入某个子目录后无法继续往下遍历，调用方永远
只能拿到空的 folders。

改为按兄弟接口的方式映射 folderInfo。

packages/napcat-onebot/action/go-cqhttp/GetGroupFilesByFolder.ts

@@ -43,7 +43,8 @@ export class GetGroupFilesByFolder extends OneBotAction<PayloadType, ReturnType>
     return {
       files: ret.filter(item => item.fileInfo)
         .map(item => OB11Construct.file(item.peerId, item.fileInfo!)),
-      folders: [],
+      folders: ret.filter(item => item.folderInfo)
+        .map(item => OB11Construct.folder(item.peerId, item.folderInfo!)),
     };
   }
 }

packages/napcat-test/groupFilesByFolder.test.ts

@@ -0,0 +1,67 @@
+// StreamBasic must be evaluated before OneBotAction: the two modules import each other,
+// and loading OneBotAction first leaves BasicStream extending an uninitialized binding.
+import '../napcat-onebot/action/stream/StreamBasic';
+import { describe, expect, test, vi } from 'vitest';
+import { GetGroupFilesByFolder } from '../napcat-onebot/action/go-cqhttp/GetGroupFilesByFolder';
+
+const FOLDER_ITEM = {
+  peerId: '123',
+  folderInfo: {
+    folderId: 'sub_folder_1',
+    folderName: '子目录',
+    createTime: 1,
+    createUin: '9',
+    creatorName: '创建者',
+    totalFileCount: 2,
+    modifyTime: 2,
+    modifyUin: '9',
+    modifyName: '修改者',
+  },
+};
+
+function createAction (items: unknown[]) {
+  const getGroupFileList = vi.fn().mockResolvedValue(items);
+  const action = new GetGroupFilesByFolder(
+    undefined as never,
+    {
+      apis: {
+        MsgApi: { getGroupFileList },
+      },
+    } as never
+  );
+  return { action, getGroupFileList };
+}
+
+describe('get_group_files_by_folder subfolders', () => {
+  test('maps folderInfo entries into folders', async () => {
+    const { action } = createAction([FOLDER_ITEM]);
+
+    const res = await action._handle({ group_id: '123', file_count: 50 });
+
+    expect(res.folders).toHaveLength(1);
+    expect(res.folders[0]).toMatchObject({
+      group_id: 123,
+      folder_id: 'sub_folder_1',
+      folder_name: '子目录',
+      total_file_count: 2,
+    });
+    expect(res.files).toHaveLength(0);
+  });
+
+  test('returns empty arrays when the folder holds nothing', async () => {
+    const { action } = createAction([]);
+
+    const res = await action._handle({ group_id: '123', file_count: 50 });
+
+    expect(res.files).toHaveLength(0);
+    expect(res.folders).toHaveLength(0);
+  });
+
+  test('passes the requested folder id through to the core API', async () => {
+    const { action, getGroupFileList } = createAction([]);
+
+    await action._handle({ group_id: '123', file_count: 50, folder_id: 'parent_1' });
+
+    expect(getGroupFileList).toHaveBeenCalledWith('123', expect.objectContaining({ folderId: 'parent_1' }));
+  });
+});