source: class SignGuestbookServletTest {
  
    private SignGuestbookServlet signGuestbookServlet;
    private final LocalServiceTestHelper helper;
  
    @Test
    public void testDoPost() throws IOException, EntityNotFoundException {
  
target:     final HttpServletRequest request = mock(HttpServletRequest.class);
      final HttpServletResponse response = mock(HttpServletResponse.class);
  
      final String guestbookName = "TestGuestbook";
      final String testContent = "Test Content";
  
      when(request.getParameter("guestbookName")).thenReturn(guestbookName);
      when(request.getParameter("content")).thenReturn(testContent);
  
      final Date priorToRequest = new Date();
  
      signGuestbookServlet.doPost(request, response);
  
      final Date afterRequest = new Date();
  
      verify(response).sendRedirect("/guestbook.jsp?guestbookName=TestGuestbook");
  
      final User currentUser = UserServiceFactory.getUserService().getCurrentUser();
  
      final Entity greeting = DatastoreServiceFactory.getDatastoreService().prepare(new Query()).asSingleEntity();
  
      assertEquals(guestbookName, greeting.getKey().getParent().getName());
      assertEquals(testContent, greeting.getProperty("content"));
      assertEquals(currentUser, greeting.getProperty("user"));
  
      final Date date = (Date) greeting.getProperty("date");
      assertTrue("The date in the entity [" + date + "] is prior to the request being performed",
          priorToRequest.before(date) || priorToRequest.equals(date));
      assertTrue("The date in the entity [" + date + "] is after to the request completed",
          afterRequest.after(date) || afterRequest.equals(date));
    }
  
  }