/** Checks if the user gets an error when trying to do double login. */
 @Test
 public void testDoubleLogin() {
   loginResponder.handleAction(new Message("login", new String[] {"pencho"}), context);
   Response expectedResponse = new ErrorResponse("err pencho already taken!");
   Response actualResponse =
       loginResponder.handleAction(new Message("login", new String[] {"pencho"}), context);
   assertEquals(expectedResponse, actualResponse);
 }
 /** Checks if the user can log in. */
 @Test
 public void testUserLogin() {
   Response actualResponse =
       loginResponder.handleAction(new Message("login", new String[] {"pencho"}), context);
   Response expectedResponse = new ResultResponse("ok pencho successfully registered!");
   assertTrue(userRegistry.isUserRegistered("pencho"));
   assertEquals(expectedResponse, actualResponse);
 }