@Test
public void getRoomMemberCount() throws Exception {

    RoomMemberCountResponse dummyResponse = RoomMemberCountResponse
            .builder()
            .count(3L)
            .build();
    whenCall(retrofitMock.getRoomMemberCount(any()),
             dummyResponse);
    // Do
    RoomMemberCountResponse got = target.getRoomMemberCount("GGGGGGGGGGGGGGGGGG")
                                        .get();
    // Verify
    verify(retrofitMock, only()).getRoomMemberCount("GGGGGGGGGGGGGGGGGG");
    assertThat(got).isEqualTo(dummyResponse);
}