stub粗粒度测试

Stub这种机制是用来模拟可能存在或还没写完的真实代码所产生的行为。它能使你顺利地测试系统的一部分，而无须考虑其它部分是否可行。通常，stub不会改变你测试的代码，只是加以适配以提供无缝整合。

Stub是代码的一部分，在运行时我们用stub替换真正的代码，忽略调用代码的实现。目的是用一个简单一点的行为替换一个复杂的行为，从而允许独立测试代码的某一部分。

我们为什么要用stub？

假设你同其他开发者一起开发一个项目，你想测试项目中你的那一部分，但其他部分还没完成，那该怎么办？解决的办法是用一个仿造品模拟缺失的那一部分。

为了使软件开发和测试同时进行，从而缩短软件的开发周期。通常会用stub代替成熟的外部系统，诸如，文件系统，到服务器的连接，数据库等。

4.1  用jetty作为嵌入式服务器代替Web服务器

JettySample.java：

import org.mortbay.http.HttpContext;

import org.mortbay.http.HttpServer;

import org.mortbay.http.SocketListener;

import org.mortbay.http.handler.ResourceHandler;

import org.mortbay.util.MultiException;

public class JettySample {

  public static void main(String[] args) {

       HttpServer server = new HttpServer();

      SocketListener listener = new SocketListener();

      listener.setPort(8080);

      server.addListener(listener);

     

      HttpContext context = new HttpContext();

      context.setContextPath("/");

      //设置资源文件的根目录

      context.setResourceBase("./");

      //添加资源处理器到httpContext，使之能提供文件系统中的文件

context.addHandler(new ResourceHandler());

      server.addContext(context);

      try {

            //启动服务器

           server.start();

       } catch (MultiException e) {

           // TODO Auto-generated catch block

           e.printStackTrace();

       }

  }

}

运行main方法：

在IE地址栏输入http://localhost:8080/

4.2  Jetty替换web服务器的例子

1.服务器代码:

import java.io.IOException;

import java.io.OutputStream;

import junit.extensions.TestSetup;

import org.mortbay.http.HttpContext;

import org.mortbay.http.HttpException;

import org.mortbay.http.HttpFields;

import org.mortbay.http.HttpRequest;

import org.mortbay.http.HttpResponse;

import org.mortbay.http.HttpServer;

import org.mortbay.http.SocketListener;

import org.mortbay.http.handler.AbstractHttpHandler;

import org.mortbay.http.handler.ResourceHandler;

import org.mortbay.util.ByteArrayISO8859Writer;

import org.mortbay.util.MultiException;

 

public class WebClientServer extends TestSetup{

  HttpServer server;

  public WebClientServer(junit.framework.Test test) {

       super(test);

  }

  //启动服务器

  protected void setUp(){

       server = new HttpServer();

      SocketListener listener = new SocketListener();

      listener.setPort(8080);

      server.addListener(listener);

      HttpContext context = new HttpContext();

      context.setContextPath("/");

      context.setResourceBase("./");

      context.addHandler(new ResourceHandler());

      //添加服务器返回信息

      context.addHandler(new TestGetConnectHandler());

      server.addContext(context);

      try {

           server.start();

       } catch (MultiException e) {

           // TODO Auto-generated catch block

           e.printStackTrace();

       }

  }

 

  //关闭服务器

  protected void tearDown(){

       try {

           server.stop();

       } catch (InterruptedException e) {

              e.printStackTrace();

       }

  }

  //设置服务器返回信息

  private class TestGetConnectHandler extends AbstractHttpHandler{

       public void handle(String path, String params, HttpRequest request,HttpResponse response) throws HttpException, IOException {

           OutputStream output = response.getOutputStream();

           ByteArrayISO8859Writer writer = new ByteArrayISO8859Writer();

           writer.write("It works");

           writer.flush();

           response.setIntField(HttpFields.__ContentLength, writer.size());

           writer.writeTo(output);

           output.flush();

           request.setHandled(true);

       }

  }

}

2.待测试类

import java.io.IOException;

import java.io.InputStream;

import java.net.*;

public class WebClient {

  public String getConnect(URL url){

       StringBuffer content = new StringBuffer();

       try {

           HttpURLConnection connection = (HttpURLConnection)url.openConnection();

           connection.setDoInput(true);

           InputStream input = connection.getInputStream();

           byte[] buffer = new byte[2048];

           int count;

           while(-1 != (count = input.read(buffer))){

                content.append(new String(buffer,0,count));

           }

       } catch (IOException e) {

           return null;

       }

       return content.toString();

  }

}

3.测试类

import java.net.MalformedURLException;

import java.net.URL;

import junit.framework.Test;

import junit.framework.TestCase;

import junit.framework.TestSuite;

 

public class WebClientTest extends TestCase{

 

  //启动服务器

  public static Test suite(){

       TestSuite suite = new TestSuite();

       suite.addTestSuite(WebClientTest.class);

       return new WebClientServer(suite);

  }             

    //启动测试

  public void testGetConnect() throws MalformedURLException {

       WebClient webClient = new WebClient();   

       String result = webClient.getConnect(new URL("http://localhost:8080/testGetConnect"));   

       assertEquals("It works",result);

  }

}

4.3替换连接

1.Http连接的处理类

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.ProtocolException;

import java.net.URL;

public class StubHttpURLConnection extends HttpURLConnection {

  private boolean isInput = true;

  protected StubHttpURLConnection(URL url){

       super(url);

  }

  @Override

  public InputStream getInputStream() throws IOException {

       if(!isInput){

           throw new ProtocolException("Cann't read from URLConnection"

                + "if(doInput =false(call setDoInput(true)))");

       }

       ByteArrayInputStream bais = new ByteArrayInputStream(new String("It works").getBytes());

       return bais;

  }

  @Override

  public void disconnect() {}

  @Override

  public boolean usingProxy() {return false;}

  @Override

  public void connect() throws IOException {}

}

 

import java.io.IOException;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLConnection;

import java.net.URLStreamHandler;

import java.net.URLStreamHandlerFactory;

import junit.framework.TestCase;

 

public class WebClientServerTwo extends TestCase{

 

    //TestCase启动时加载

  protected void setUp(){

       //告诉url类用工厂来处理连接

       URL.setURLStreamHandlerFactory(new StubStreamHandlerFactory());

  }

 

  private class StubStreamHandlerFactory implements URLStreamHandlerFactory{

       //把所有链接连到http处理器

       public URLStreamHandler createURLStreamHandler(String protocol) {

           return new StubHttpURLStreamHandler();

       }

  }

 

  private class StubHttpURLStreamHandler extends URLStreamHandler{

       protected URLConnection openConnection(URL url) throws IOException {

           //httpConnection处理器

           return new StubHttpURLConnection(url);

       }

  }

 

  public void testGetConnect() throws MalformedURLException {

       WebClient webClient = new WebClient();

       String result = webClient.getConnect(new URL("http://www.baidu.com"));   

       assertEquals("It works",result);

  }

}