@Test
public void getGroupSummary() throws Exception {

    GroupSummaryResponse dummyResponse = GroupSummaryResponse
            .builder()
            .build();
    whenCall(retrofitMock.getGroupSummary(any()),
             dummyResponse);
    // Do
    GroupSummaryResponse got = target.getGroupSummary("GGGGGGGGGGGGGGGGGG")
                                     .get();
    // Verify
    verify(retrofitMock, only()).getGroupSummary("GGGGGGGGGGGGGGGGGG");
    assertThat(got).isEqualTo(dummyResponse);
}