我试着为我的班级做一个模拟测试，但它不起作用。
原始类：

public class Service {
  .................
  @POST
  ...
  public Message Info(@NotNull @Valid final UUID Id) throws IOException {
    ............
    String httpLink = Config.getLink();
    ...
    if ( ...) { 
      HttpURLConnection urlConnection = null;
      URL url = new URL(OriginalLink);
      urlConnection = (HttpURLConnection) url.openConnection();
      urlConnection.setDoOutput(true);
      urlConnection.setRequestMethod("GET");
      urlConnection.setUseCaches(false);
      urlConnection.setConnectTimeout(50000);
      urlConnection.setReadTimeout(50000);
      urlConnection.setRequestProperty("Content-Type", "application/json");
      urlConnection.connect();
      .................
      String jsonobject = "..."; //data to be posted into api
      .......
    } else {
      return new Message("No data to posted from file");
    }
    return new Message("successfully posted data from file");
  }
}

测试类别：

@Before
public void before() {
  MockitoAnnotations.initMocks(this);
  URL u = PowerMockito.mock(URL.class);
  String url = "url";
  PowerMockito.whenNew(URL.class).withArguments(url).thenReturn(u);
  HttpURLConnection huc = PowerMockito.mock(HttpURLConnection.class);
  PowerMockito.when(u.openConnection()).thenReturn(huc);
  PowerMockito.when(huc.getResponseCode()).thenReturn(200);
  .....
  PowerMockito.when(Config.getLink())
    .thenReturn("url");
}
 @Test
 public void testInfo() throws IOException {
    ............
    Message org = new Message("successfully posted data from file");
    Message msg = Service.Info(uuid);
    assertEquals(msg,org);
 }

我尝试使用Mockito和PowerMockRunner进行模拟，但没有成功。使用PowerMockito时，我得到“java.lang.NullPointerException”