Wrong return value from 'property var' functions

import QtQuick 2.0

Rectangle {
    width: 360
    height: 360

    property var f1 : function () {
        console.log("Test case 1");
        return 100;
    }
    property var f2;
    function testcase2() {
        console.log("Test case 2");
        return 200;
    }
    Component.onCompleted: {
        f2 = testcase2;
        console.log('f1 :'+f1);
        console.log('f2 :'+f2);
    }
}