我对所有最新的JMockit注入工具都不熟悉，因此我使用了JMockits对伪造"的支持.

I'm not familiar with all the latest JMockit injection stuff, so I used JMockits support for "fakes".

@RunWith(JMockit.class)
public class ImageServletTest3 {

     @Test
    public void testImageNotFound() throws Exception {
        ImageServlet servlet = new ImageServlet();

        servlet.doGet(
            new MockUp<HttpServletRequest>() {
              @Mock
              public String getParameter(String id){
                return null;
              }

            }.getMockInstance(),
            new MockUp<HttpServletResponse>() {
              @Mock
              public void sendError(int num){
                Assert.assertThat(num, IsEqual.equalTo(404));               
              }             
            }.getMockInstance()
       );
    }

}