如何使用Mockito模擬注入對象的屬性

Question

我想測試方法deleteTracks ，為此，我需要模擬一個在調用playlistDaoBean.getPlaylistByUUID(uuid)之后檢索的playlistDaoBean.getPlaylistByUUID(uuid)

public class PlaylistBusines {

private PlaylistDao playlistDao;

@Inject
public PlaylistBusinessBean(PlaylistDaoBean playlistDaoBean){
    this.playlistDaoBean = playlistDaoBean;
}

List<PlayListTrack> deleteTracks(String uuid, List<Integer> indexes) throws PlaylistException {


    PlayList playList = playlistDaoBean.getPlaylistByUUID(uuid);
    // TODO

}

這是我的課堂測試：

public class PlaylistBusinessTest {

    @Inject
    PlaylistBusinessBean playlistBusinessBean;


     @Test
    public void testRemoveTracks() throws Exception {

    PlayList playList = new PlayList();
    playList.setId(222)
    playList.setName("fake name");


    PlaylistDaoBean playlistDaoBeanMock = mock(PlaylistDaoBean.class);
    when(playlistDaoBeanMock.getPlaylistByUUID(uuid)).thenReturn(playList);


    playlistBusinessBean.removeTracks(uuid, Arrays.asList(2, 3));


    }

Answer 1

被測實例（PlaylistBusinessBean）由DI框架注入。 但是，那是不使用測試中創建的PlaylistDaoBean的模擬。 模擬只是局部變量，在任何地方都沒有使用。

與其使用注入的PlaylistBusinessBean實例，不如通過編程方式創建一個實例並將PlaylistDaoBean模擬傳遞給它：

public class PlaylistBusinessTest {

     @Test
    public void testRemoveTracks() throws Exception {

    PlayList playList = new PlayList();
    playList.setId(222)
    playList.setName("fake name");


    PlaylistDaoBean playlistDaoBeanMock = mock(PlaylistDaoBean.class);
    when(playlistDaoBeanMock.getPlaylistByUUID(uuid)).thenReturn(playList);

    PlaylistBusinessBean playlistBusinessBean = new PlaylistBusinessBean(playlistDaoBeanMock);

    playlistBusinessBean.removeTracks(uuid, Arrays.asList(2, 3));


    }

一般注意事項：

• 這是一個單元測試，因此我總是建議您獨立於DI和任何注入的代碼獨立地測試代碼。
• 但是，如果確實需要，通常還可以使用特定於測試的DI上下文，該上下文在需要時將模擬注入到受測試的bean。 該如何做取決於所使用的DI。

Answer 2

這不起作用的原因是您沒有將模擬作為參數提供給PlaylistBusines。

值得提供錯誤，但是您定義行為的模擬程序永遠不會在被測類中使用。