模拟抛出空指针异常.新来的mockito

Question

我正在尝试测试以下方法

  MainClass {
    ....
        Client client;
        WebTarget target;
        boolean doLogin(MultivaluedMap<String, String> headers) {

             client = getRestClient();
             target = client.target(BASE_URL))
                    .path("v1/login");
              MultivaluedMap<String, Object> castedHeaders = castMap(headers);//casts headers by entry.
              Response loginRsp = target
                    .request().headers(castedHeaders)     
                    .post(Entity.entity(buildIusLoginEntity(),
                                        MediaType.APPLICATION_JSON_TYPE));
              if (loginRsp.getStatus() != HttpServletResponse.SC_OK) {

                    return false;
              }
              return true;
        }
   }

使用以下测试类

  @Test
  public void testdoLoginNegative() {
            MainClass m = spy(new MainClass());
            Client mockClient = mock(Client.class);
            WebTarget target = mock(WebTarget.class);

            Response loginRsp = Response.status(500).build();
            doReturn(mockClient).when(m).getRestClient();
            when(mockClient.target(anyString()).path(anyString())).thenReturn(target);
            //NPE on next line.
            when(target.request().headers(any(MultivaluedMap.class)).post(any(Entity.class))).thenReturn(loginRsp);// this line throws a Null pointer exception. 
            Assert.assertFalse(m.doIusLogin(getMockHeaders()));
   }

但是,我的模拟似乎显示了源代码中指示的空指针异常.任何关于我可能做错的想法......都将不胜感激.

Answer 1

您尝试使用深度存根而不准备模拟对象.尝试

 WebTarget target = mock(WebTarget.class, Mockito.RETURNS_DEEP_STUBS);

不同之处在于,没有深度存根的模拟返回方法调用的默认值(通常为null).如果你附上这样的调用Mockito.when没有效果,但如果你追加进一步的调用,这会导致NullPointerExceptions,例如在

target
  .request()                          // return null
  .headers(any(MultivaluedMap.class)) // NullPointerException
  .post(any(Entity.class)))

不过我希望如此

mockClient
  .target(anyString())                // should return null
  .path(anyString()))                 // should throw NullPointerException

失败NullPointerException,没有激活深层存根

Client mockClient = mock(Client.class, Mockito.RETURNS_DEEP_STUBS);

并非激活深度存根可能对编写测试很方便,但它可能导致测试代码中的奇怪行为.