Exemplo de Testabilidade - Servlet

IMCServlet.java

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

class IMCModel {
  public double calculaIMC(String p1, String a1) 
         throws NumberFormatException {
    double p = Double.parseDouble(p1);
    double a = Double.parseDouble(a1);
    double imc = p / (a * a);
    return Math.floor(imc * 100) / 100; 
  }
}

public class IMCServlet extends HttpServlet  { 
  
  IMCModel model = new IMCModel();
 
  public void doGet(HttpServletRequest req, HttpServletResponse res) 
         throws IOException, ServletException {
	  
    res.setContentType("text/html"); 
    PrintWriter out = res.getWriter(); 
    String peso = req.getParameter("peso");
    String altura = req.getParameter("altura");
    try { 
      double imc = model.calculaIMC(peso, altura); 
      out.println("IMC: " + imc); 
    } 
    catch (NumberFormatException e) { 
      out.println("Dados devem ser numéricos"); 
    } 
  }
}