Struts2 Junit Plugin (StrutsTestCase) request object is Null

I am using the Struts2 JUnit Plugin (v2.3.20) struts2 (v.2.3.20) and have issues in my test class code.

I have List of jar files in my classpath:

-spring-beans-4.1.0.RELEASE.jar
-spring-context-4.1.0.RELEASE.jar
-spring-core-4.1.0.RELEASE.jar
-spring-mock-2.0.8.jar
-spring-test-4.1.0.RELEASE.jar
-spring-web-4.1.0.RELEASE.jar
-struts2-core-2.3.20.jar
-struts2-junit-plugin-2.3.20.jar
-struts2-spring-plugin-2.3.20.jar
-xwork-core-2.3.20.jar
-junit-4.12.jar

My struts.xml Action looks like the following:

 <action name="createaccount" class="com.AccountAction">
            <result name="success">/thankyou.jsp</result>
            <result name="input">/createaccount.jsp</result>
 </action>

And my Action class is as follows:

  package com;
   import java.util.logging.Logger;
   import com.opensymphony.xwork2.ActionSupport;

    public class AccountAction extends ActionSupport {

    String userName;
    String password;
    private static final long serialVersionUID = 1L;
    private static final Logger logger = Logger.getLogger( AccountAction.class.getName() );
    //private Account accountBean;
    public String execute(){
        System.out.println("Execute Method");
        return SUCCESS;
    }

  //Setter and getter methods for username and password
    ....
    ....

}

And my Test class is as follows:

package com;

import org.apache.struts2.StrutsTestCase;
import com.opensymphony.xwork2.ActionProxy;

public class TestAccountActionUsingStrutsTestCase extends StrutsTestCase {

     public void testUserNameCorrect() throws Exception {

         /**Here Request is coming null and it is throwing NullPointerException**/
//Exception here NullPointerException
//Exception here NullPointerException
            request.setParameter("userName", "Bruce");
            request.setParameter("password", "test");

        ActionProxy proxy = getActionProxy("/createaccount");

        AccountAction accountAction = (AccountAction) proxy.getAction();

        String result = proxy.execute();

        assertTrue("Problem There were errors present in fieldErrors but there should not have been any errors present", accountAction.getFieldErrors().size() == 0);
        assertEquals("Result returned form executing the action was not success but it should have been.", "success", result);

    }
      public static void main(String[] args) throws Exception {
        TestAccountActionUsingStrutsTestCase test=new TestAccountActionUsingStrutsTestCase();
        test.testUserNameCorrect();
    }
    }

I use Spring within my struts app, and these jars are needed to use the mock request object and the StrutsTestCase.

As I commented in the above test class code , request is null in StrutsTestCase. Why is this?

Is that ritht place to put main method in Test class.? I am using right method of unit testing for sturts 2 and spring ?

and also why is request null? Any help will be Appreciated!