Use jmock to perform unit tests on the httpservlet class

1. Create an uploadservlet class

package com.anllin.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.output.Format;
import static com.anllin.servlet.XmlUtils.*;

public class UploadServlet extends HttpServlet
{
private static final long serialVersionUID = 7320350794641788612L;

    @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        String ipAndPort = String.format("http://%s:%s", req.getServerName(), req.getLocalPort());
        String serviceProviderXml = constructResponseXMl(ipAndPort);
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/xml");
        PrintWriter out = resp.getWriter();
        out.append(serviceProviderXml);
        out.flush();
        out.close();
    }

    @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        doGet(req, resp);
    }

protected String constructResponseXMl(String ipAndPort)
    {
        Document doc = ConstructDocument();
        Element root = constructElement("ServiceProvider");
        doc.addContent(root);

        Element title = constructElement("title", "Test");
        Element description = constructElement("description", "Upload data in everyday");
        Element url = constructElement("url", ipAndPort + "/test/upload");

        constructChildTree(root, title, description, url);

        Format format = getFormat("utf-8", "    ");
        String xml = getXMLStringFromDocunment(doc, format);
return xml;
    }
}

2. Create a helper class xmlutils

package com.anllin.servlet;

import java.io.StringReader;
import java.util.Arrays;
import java.util.List;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;

public class XmlUtils
{
public static Element parse(String xml)
    {
try
        {
            SAXBuilder builder = new SAXBuilder();
            StringReader sr = new StringReader(xml);
            Document doc = builder.build(sr);
return doc.getRootElement();
        }
catch (Exception e)
        {
throw new RuntimeException(e);
        }
    }

public static Document ConstructDocument()
    {
return new Document();
    }

public static Element constructElement(String name)
    {
return new Element(name);
    }

public static Element constructElement(String name, String text)
    {
return new Element(name).setText(text);
    }

public static Element constructChildTree(Element father, Element... childs)
    {
        List<Element> list = Arrays.asList(childs);
        father.addContent(list);
return father;
    }

public static Format getFormat(String encoding, String indent)
    {
return Format.getPrettyFormat().setEncoding(encoding).setIndent(indent);
    }

public static XMLOutputter getXMLOutputter(Format format)
    {
return new XMLOutputter(format);
    }

public static String getXMLStringFromDocunment(Document doc, Format format)
    {
return getXMLOutputter(format).outputString(doc);
    }
}

3. Create a mockedtests class

package com.anllin.servlet;

import org.jmock.Mockery;
import org.jmock.integration.junit4.JMock;
import org.jmock.integration.junit4.JUnit4Mockery;
import org.junit.runner.RunWith;

@RunWith(JMock.class)
public class MockedTests
{
protected Mockery mockery = new JUnit4Mockery();
}

4. Use jmock for testing

package com.anllin.servlet;

import static org.junit.Assert.*;

import java.io.ByteArrayOutputStream;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.jdom.Element;
import org.jmock.Expectations;
import org.junit.Before;
import org.junit.Test;

public class UploadServletTest extends MockedTests
{
private UploadServlet uploadServlet;
private HttpServletRequest req;
private HttpServletResponse resp;
private ByteArrayOutputStream out;

    @Before
public void setUp() throws Exception
    {
        uploadServlet = new UploadServlet();
        req = mockery.mock(HttpServletRequest.class);
        resp = mockery.mock(HttpServletResponse.class);
        out = new ByteArrayOutputStream();
    }

    @Test
public void testDoGet() throws Exception
    {
        mockery.checking(new Expectations()
        {
            {
                one(req).getServerName();
                will(returnValue("192.168.0.62"));

                one(req).getLocalPort();
                will(returnValue(8080));

                one(resp).setCharacterEncoding("utf-8");
                one(resp).setContentType("text/xml");

                PrintWriter writer = new PrintWriter(out);
                allowing(resp).getWriter();
                will(returnValue(writer));
            }
        });

        uploadServlet.doGet(req, resp);
        Element root = XmlUtils.parse(out.toString());
        assertTrue(root.getChildren().size() > 0);
    }
}

The test result is output as follows:

<?xml version="1.0" encoding="utf-8"?>
<ServiceProvider>
<title>Test</title>
<description>Upload data in everyday</description>
<url>http://192.168.0.62:8080/test/upload</url>
</ServiceProvider>