update tests

__mocks__/matrix-js-sdk.js

@@ -151,7 +151,7 @@ export const mockGetJoinedRoomMembers = jest.fn(() => {
 
 export const mockGetGroupUsers = jest.fn(() => {
   return Promise.resolve({
-    chunk: { user_id: 'user_id_1', user_id: 'user_id_2' }
+    chunk: [{ user_id: 'user_id_1'}, { user_id: 'user_id_2' }]
   })
 });