我有一个名为的servlet Calculator。它读取参数left，right并op通过result在响应中设置属性来返回。

对此进行单元测试的最简单方法是什么：基本上我想创建一个HttpServletRequest，设置参数，然后检查响应-但是我该怎么做？

这是servlet代码（它小巧而故意）：

public class Calculator extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
public Calculator() {
    super();
}       
protected void doGet(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
}   
protected void doPost(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
    Integer left = Integer.valueOf(request.getParameter("left"));
    Integer right = Integer.valueOf(request.getParameter("right"));
    Integer result = 0;
    String op = request.getParameter("operator");
    if ("add".equals(op)) result = this.opAdd(left, right);
    if ("subtract".equals(op)) result = this.opSub(left, right);
    if ("multiply".equals(op)) result = this.opMul(left, right);
    if ("power".equals(op)) result = this.opPow(left, right);
    if ("divide".equals(op)) result = this.opDiv(left, right);
    if ("modulo".equals(op)) result = this.opMod(left, right);

    request.setAttribute("result", result); // It'll be available as ${sum}.
    request.getRequestDispatcher("index.jsp").forward(request, response);
    }
}
...

}