### Question:
LeaderBoardServiceImpl implements LeaderBoardService { @Override public List<LeaderBoardRow> getCurrentLeaderBoard() { return scoreCardRepository.findFirst10(); } LeaderBoardServiceImpl(ScoreCardRepository scoreCardRepository); @Override List<LeaderBoardRow> getCurrentLeaderBoard();  }### Answer:
@Test public void retrieveLeaderBoardTest() { Long userId = 1L; LeaderBoardRow leaderRow1 = new LeaderBoardRow(userId, 300L); List<LeaderBoardRow> expectedLeaderBoard = Collections.singletonList(leaderRow1); given(scoreCardRepository.findFirst10()).willReturn(expectedLeaderBoard); List<LeaderBoardRow> leaderBoard = leaderBoardService.getCurrentLeaderBoard(); assertThat(leaderBoard).isEqualTo(expectedLeaderBoard); }