TestCase mouseClick() doesn't work properly

// code placeholder
import QtQuick 2.0
import QtTest 1.0
import QtQuick.Controls 2.0

TestCase { 
   id: root 
   name: "ClickTest" 
   when: windowShown  

   property Component component_button: Button { 
                        onClicked: print("button clicked") 
                        }  


   function test_button() {  
     var item = createTemporaryObject(component_button, root);
     // here, the print is not working
     mouseClick(item, item.width/2, item.height/2);  

     // here, the print is working
     item.clicked(); 
     } 
}