how to do servlet unit testing

hi guys i need help from you, i created chillist servlet for reading properties from /content it returns a JSONArray of the node's child node paths and properties.

so plz help for unit testing. i need unit testing script for this code, this my code

package com.aem.community.core.servlets;

import java.io.IOException;

import javax.jcr.Node;

import javax.jcr.NodeIterator;

import javax.jcr.RepositoryException;

import javax.servlet.ServletException;

import org.apache.felix.scr.annotations.Service;

import org.apache.felix.scr.annotations.sling.SlingServlet;

import org.apache.sling.api.SlingHttpServletRequest;

import org.apache.sling.api.SlingHttpServletResponse;

import org.apache.sling.api.resource.Resource;

import org.apache.sling.api.resource.ResourceResolver;

import org.apache.sling.api.servlets.SlingAllMethodsServlet;

import org.apache.sling.commons.json.JSONArray;

import org.apache.sling.commons.json.JSONException;

import org.apache.sling.commons.json.JSONObject;

import org.apache.sling.commons.json.jcr.JsonJcrNode;

import org.osgi.service.component.annotations.Component;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

@Component(enabled = true, immediate = true)

@Service(ChildList.class)

@SlingServlet(resourceTypes="sling/servlet/default",selectors="childlist",methods="GET",extensions="json",metatype=true)

public class ChildList extends SlingAllMethodsServlet {

protected final Logger loger = LoggerFactory.getLogger(ChildList.class);

private static final long serialVersionUID = 9176255033916949528L;

private JSONArray array;

@Override

public void doGet(final SlingHttpServletRequest request, final SlingHttpServletResponse response)

throws ServletException, IOException {

try{

ResourceResolver resolver = request.getResourceResolver();

Resource resource = resolver.getResource(request.getRequestPathInfo().getResourcePath());

Node node = null;

if (resource != null) {

node = resource.adaptTo(Node.class);

}

if (node == null){

throw new RepositoryException();

}

NodeIterator it = node.getNodes();

array = new JSONArray();

while (it.hasNext()) {

Node child = it.nextNode();

if (loger.isDebugEnabled()){

loger.debug("resource......."+child.getPath());

}

JSONObject obj = new JsonJcrNode(child);

array.put(obj);

response.setContentType("application/json");

response.getOutputStream().print(array.toString());

}

}

catch(RepositoryException e) {

throw new ServletException("404 HTTP ERROR Page Not Found", e);

}

catch(JSONException e)

{

loger.error("Could not formulate JSON response");

throw new ServletException("Error", e);

}

}

}