Exemplo de teste de servlet usando mocks

IMCServeletTest.java

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

import org.junit.*;
import org.junit.Test;
import static org.junit.Assert.*;

import org.mockito.Mockito;
import static org.mockito.Mockito.when;

public class IMCServletTest {

  HttpServletRequest req;
  HttpServletResponse res;
  StringWriter sw;
  
  @Before
  public void init() {
	 try {
	    req = Mockito.mock(HttpServletRequest.class);
	    res = Mockito.mock(HttpServletResponse.class);
	    sw = new StringWriter();
	    PrintWriter pw = new PrintWriter(sw);
	    when(res.getWriter()).thenReturn(pw);
	 }
	   catch (Exception e) {}
	 } 

	@Test
	public void testDoGet() {
	  try {
		when(req.getParameter("peso")).thenReturn("82");
		when(req.getParameter("altura")).thenReturn("1.80");
        new IMCServlet().doGet(req,res);
        assertEquals("IMC: 25.3\n", sw.toString());
  
	  }
	  catch (Exception e) {}
	}

}