From Gossip@caterpillar

JUnit Gossip: 測試 Filter

如果您想測試Filter，可以繼承FilterTestCase，這個類別讓您可以使用一些由 Container管理的物件，request、 response、config、filterChain可以讓您分別取得HttpServletRequestWrapper、 HttpServletResponseWrapper、org.apache.cactus.server.FilterConfigWrapper （繼承自FilterConfig）與FilterChain物件。

直接來看個實例，假設您要撰寫一個可以過濾非法IP位址的Filter，您為這個Filter先撰寫一個測試案例：
  •  IPAddressFilterTest.java
package onlyfun.caterpillar.test;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import onlyfun.caterpillar.IPAddressFilter;

import org.apache.cactus.FilterTestCase;
import org.apache.cactus.WebResponse;

public class IPAddressFilterTest extends FilterTestCase {
    private FilterChain chain;
    
    public void setUp() {
        chain = new FilterChain() {
            public void doFilter(ServletRequest req, 
                                 ServletResponse res) 
                     throws IOException, ServletException {
                res.getWriter().print("Legal IP Address");
            }
        };
    }
    
    public void tearDown() {
        chain = null;
    }
    
    public void testLegalIPAddress() 
                      throws IOException, ServletException {
        IPAddressFilter ipFilter = new IPAddressFilter();
        ipFilter.doFilter(request, response, chain);
    }
    public void endLegalIPAddress(WebResponse webResponse) {
        assertTrue(webResponse.getText().
                         equals("Legal IP Address"));
    }
    
    public void testIllegalIPAddress() 
                      throws IOException, ServletException {
        request.setRemoteIPAddress("123.123.123.123");
        IPAddressFilter ipFilter = new IPAddressFilter();
        ipFilter.doFilter(request, response, chain);
    }
    
    public void endIllegalIPAddress(WebResponse webResponse) {
        assertTrue(webResponse.getText().
                         equals("Illegal IP Address"));
    }
}

由測試案例中可以看出Filter將實現的功能，當合法的IP來源請求時，過濾IP位址的Filter將不作任何的限制，而直接呼叫下一個Filter （或Servlet等），在這邊您自行提供一個簡單的FilterChain實作，其目的是傳回一個"Leagal IP Address"字串，以供我們作斷言測試，而如果是非法IP位址的話，中斷Filter進行下一步，所以您會收到一個"Illegal IP Address"而不是"Leagal IP Address"。

依照測試案例，您完成IPAddressFilter：
  •  IPAddressFilter.java
package onlyfun.caterpillar;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class IPAddressFilter implements Filter {
    public void init(FilterConfig config) 
                      throws ServletException {
    }

    public void doFilter(ServletRequest request,
                         ServletResponse response, 
                         FilterChain chain) 
                  throws IOException, ServletException {
        if(request.getRemoteAddr().equals("123.123.123.123")) {
            response.getWriter().print("Illegal IP Address");
        }
        else {
            chain.doFilter(request, response);
        }
    }

    public void destroy() {
        
    }
}

這邊將使用Tomcat進行測試，請參考 第一個 Cactus + Tomcat 測試 瞭解如何設定，另外，還要加上FilterRedirector設定，您要在web.xml中加上：
  • web.xml
...
 <filter>
    <filter-name>FilterRedirector</filter-name>
        <filter-class>
            org.apache.cactus.server.FilterTestRedirector
        </filter-class>
 </filter>

 <filter-mapping>
    <filter-name>FilterRedirector</filter-name>
    <url-pattern>/FilterRedirector</url-pattern>
 </filter-mapping>
...

以下是測試的結果：
測試Filter