如何使用 jUnit 对 Servlet 过滤器进行单元测试? [英] How do I unit test a Servlet Filter with jUnit?

问题描述

已实现doFilter().如何使用 jUnit 正确覆盖过滤器?

Implemented doFilter(). How to properly cover Filter with jUnit ?

public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
        throws java.io.IOException, javax.servlet.ServletException
{
    HttpServletRequest request = (HttpServletRequest) servletRequest;
    HttpServletResponse response = (HttpServletResponse) servletResponse;
    String currentURL = request.getRequestURI();

    if (!currentURL.equals("/maintenance.jsp") && modeService.getOnline())
    {
        response.sendRedirect("/maintenance.jsp");
    }
    filterChain.doFilter(servletRequest, servletResponse);
}

推荐答案

ServletRequest, ServletResponse 和 FilterChain 都是接口，所以你可以手动或使用模拟框架轻松为它们创建测试存根.

ServletRequest, ServletResponse and FilterChain are all interfaces, so you can easily create test stubs for them, either by hand or using a mocking framework.

使模拟对象可配置，以便您可以准备对 getRequestURI() 的预设响应，以便您可以查询 ServletResponse 以断言 sendRedirect 已被调用.

Make the mock objects configurable so that you can prepare a canned response to getRequestURI() and so that you can query the ServletResponse to assert that sendRedirect has been invoked.

注入一个模拟 ModeService.

Inject a mock ModeService.

调用 doFilter 并传递模拟 ServletRequest、ServletResponse 和 FilterChain 作为其参数.

Invoke doFilter passing the mock ServletRequest, ServletResponse and FilterChain as its parameters.

@Test
public void testSomethingAboutDoFilter() {
    MyFilter filterUnderTest = new MyFilter();
    filterUnderTest.setModeService(new MockModeService(ModeService.ONLINE));
    MockFilterChain mockChain = new MockFilterChain();
    MockServletRequest req = new MockServletRequest("/maintenance.jsp");
    MockServletResponse rsp = new MockServletResponse();

    filterUnderTest.doFilter(req, rsp, mockChain);

    assertEquals("/maintenance.jsp",rsp.getLastRedirect());
}

在实践中，您需要将设置移动到@Before setUp() 方法中，并编写更多@Test 方法来覆盖所有可能的执行路径.

In practice you'll want to move the setup into an @Before setUp() method, and write more @Test methods to cover every possible execution path.

...而且您可能会使用像 JMock 或 Mockito 这样的模拟框架来创建模拟，而不是假设的 MockModeService 等.我在这里使用过.

... and you'd probably use a mocking framework like JMock or Mockito to create mocks, rather than the hypothetical MockModeService etc. I've used here.

这是一种单元测试方法，而不是集成测试.您只是在测试被测单元(和测试代码).

This is a unit testing approach, as opposed to an integration test. You are only exercising the unit under test (and the test code).

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