java - 如何模拟ServletContext而不是Servlet或HttpServletRequest？

我有一个独立的项目来编写测试用例；问题是我无法模拟HttpServletRequest，这仅仅是因为在我的servlet中有像getServletContext()这样的调用，因为测试用例是从外部servlet容器中运行的。它将始终返回一个错误，指出“未找到上下文”。这只是servlet容器的一种依赖关系。可能有数百个。例如，initialContext.lookup()也取决于容器。

在这种情况下，如何使用Mockito编写测试用例？请不要询问错误消息；这更多的是逻辑上的问题，而不是技术上的问题。

在互联网上查找教程使我想知道我是否在做严重错误的事情。似乎没有人以前遇到过这个问题。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。我的意思是说，这有多少稀有？

最佳答案

您有一个使用ServletContext的servlet实现，例如

public class SomeServlet extends HttpServlet{

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        Object attribute = servletContext.getAttribute("test");
        System.out.println(attribute.toString());
   }
}

在这种情况下，您有2个选项可以测试doGet方法

使用powermock的partitial mocking仅模拟getServletContext方法。

@RunWith(PowerMockRunner.class)
public class SomeServletTest {

    @Test
    public void onGet() throws ServletException, IOException{
        SomeServlet someServlet = PowerMock.createPartialMock(SomeServlet.class, "getServletContext");
        ServletContext servletContext = PowerMock.createNiceMock(ServletContext.class);
        HttpServletRequest httpServletRequest = PowerMock.createNiceMock(HttpServletRequest.class);
        HttpServletResponse httpServletResponse = PowerMock.createNiceMock(HttpServletResponse.class);

        someServlet.getServletContext();
        PowerMock.expectLastCall().andReturn(servletContext);

        servletContext.getAttribute("test");
        PowerMock.expectLastCall().andReturn("hello");

        PowerMock.replay(someServlet, servletContext, httpServletRequest, httpServletResponse);

        someServlet.doGet(httpServletRequest, httpServletResponse);
    }
}

或更简单的方法是仅覆盖getServletContext方法。在这种情况下，您不需要powermock。您可以使用easymock做到这一点。例如

public class SomeServletTest {

    @Test
    public void onGet() throws ServletException, IOException{
        HttpServletRequest httpServletRequest = EasyMock.createNiceMock(HttpServletRequest.class);
        HttpServletResponse httpServletResponse = EasyMock.createNiceMock(HttpServletResponse.class);
        final ServletContext servletContext = EasyMock.createNiceMock(ServletContext.class);
        SomeServlet someServlet = new SomeServlet(){
            public ServletContext getServletContext() {
                return servletContext; // return the mock
            }
        };

        EasyMock.expect(servletContext.getAttribute("test")).andReturn("hello");
        EasyMock.replay(servletContext, httpServletRequest, httpServletResponse);

        someServlet.doGet(httpServletRequest, httpServletResponse);
    }
}

在这种情况下，您可以创建一个InitialContext模拟并使用它。
如果您的代码创建了新的InitialContext，例如

public void someMethod(){
    InitialContext context = new InitialContext();
    context.lookup(....);
}

您可以简单地将InitialContext实例提取到一个 protected 方法，您可以在测试中覆盖该方法，就像我上面用ServletContext显示的那样

public void someMethod(){
    InitialContext context = createInitialContext();
    context.lookup(....);
}

protected InitialContext createInitialContext(){
    return new InitialContext(); // can be overridden by a subclass
                                 // and therefore by tests as well to
                                 // return a mock
}

如果您不希望或者无法以这种方式修改代码，则可以使用Powermock到intercept the constructor。

编辑

@Test
public void onGet() throws ServletException, IOException {
  HttpServletRequest httpServletRequest = Mockito.mock(HttpServletRequest.class);
  HttpServletResponse httpServletResponse = Mockito.mock(HttpServletResponse.class);
  final ServletContext servletContext = Mockito.mock(ServletContext.class);
  SomeServlet someServlet = new SomeServlet(){
    public ServletContext getServletContext() {
      return servletContext; // return the mock
    }
  };

  Mockito.doReturn("hello").when(servletContext).getAttribute("test");

  someServlet.doGet(httpServletRequest, httpServletResponse);
}