qmltestrunner can't handle drag event as expected

import QtQuick 2.0
import QtTest 1.0

Rectangle{
    id: root
    width:200
    height:200

    Rectangle {
        id:container
        width:20
        height:20
        color: "blue"
        MouseArea {
            id:mouseArea; anchors.fill : parent
            drag.maximumX: 180
            drag.maximumY: 180
            drag.minimumX: 0
            drag.minimumY: 0
            drag.target: parent
            onReleased: {
                console.log("released:" + mouse.x + "," + mouse.y);
                if(parent.x > 10){ console.log("dragged") }
            }
        }
    }

    TestCase {
        name:"mouserelease"
        when:windowShown
        function test_mouseRelease() {
            mousePress(container, 0, 0);
            mouseMove(container, 50, 50);
            //mouseMove(container, 0, 0);//without this second moveMove, the test will fail
            compare(container.x, 50);
            compare(container.y, 50);
        }
    }
}