message: mock getMembers on mkStubRoom
diff: @@ -234,6 +234,7 @@ export function mkStubRoom(roomId = null) {
  }),
  getMembersWithMembership: jest.fn().mockReturnValue([]),
  getJoinedMembers: jest.fn().mockReturnValue([]),
  + getMembers: jest.fn().mockReturnValue([]),
  getPendingEvents: () => [],
  getLiveTimeline: () => stubTimeline,
  getUnfilteredTimelineSet: () => null,
  