anchor.diff:        var pathOld = routeOneParameter.path(paramsOld);
         var pathNew = routeOneParameter.path(paramsNew);
   
  -      var view = new ViewMock();
  -      var historyAsync = new HistoryAsyncMock(null, pathNew);
  +      var view = new ViewSpy(new DummyView());
  +      var historyTest = new DummyTestHistory("", pathNew)
  +        ..test = false;
  +      var historyAsync = new AsyncHistoryMock(historyTest);
         var navigator = new PageNavigator(router, historyAsync);
   
         navigator.registerView(routeNameOneParameter, view);
  
positive.code: 
        // page navigator state
        history.getLogs(callsTo("replaceState")).verify(happenedExactly(++historyReplaceCalls));
  
        // histoty state
        expect(history.url, equals(pathStatic));
  
        // view methods called correctly
        viewStatic.getLogs(callsTo("load")).verify(happenedOnce);
        expect(viewStatic.getLogs(callsTo('load')).first.args.first.toJson(), equals(params));
  
        viewStatic.getLogs(callsTo("unload")).verify(happenedExactly(0));
      });
  
negative.code: 
        //check if set up is correct
        expect(navigator.activePath, equals(pathOld));
        expect(view.getLogs(callsTo('load')).last.args.first.toJson(), equals(paramsOld));
        historyTest.test = true;
  
        //==when
        view._real.data.add(paramsNew.keys.first, paramsNew.values.first);
  
        //==then
        //check if history is updated correctly
  