grabToImage not working when using qmltestrunner.exe - qt

Question

newbee here on QML. Apologies if the question is too basic but I am stuck.
I am trying something very simple, running a simple QML unit test, but it needs to grab the image of the window and saved to the file system.
So I was looking at this tutorial and the following docs:
https://www.youtube.com/watch?v=8EUjXQzFfoA
https://doc.qt.io/qt-6/qml-qttest-testcase.html
and tried to combine both as such:
Item {
width: 800
height: 600
MyWindow
{
id: myWindowTest
}
TestCase{
name: "TestButtonClick"
when: windowShown
function test_ClickButton()
{
var notSavedText = "Not saved"
var savedText = "Saved!"
myWindowTest.grabToImage(function(result) {
console.log(result)
result.saveToFile("something.png");
});
console.log("step 1")
verify(myWindowTest.saveStatus === notSavedText, "Save status failed!")
console.log("sending click")
mouseClick(myWindowTest.saveButton)
console.log("step 2")
verify(myWindowTest.saveStatus === savedText, "Save status failed!")
}
}
}
yet the ".png" is never generated. See the output of "qmltestrunner.exe"
any clues what I don't get the image, notice that the logs are never called so it failed, but the ids look correct to me.
thank you very much!

Answer 1

In case you don't insist on using your call-method - the given method in docs works just fine for me:
var image = grabImage(rect);
try {
compare(image.width, 100);
} catch (ex) {
image.save("debug.png");
throw ex;
}
Which would result in this for you:
Item {
width: 800
height: 600
MyWindow
{
id: myWindowTest
}
TestCase{
name: "TestButtonClick"
when: windowShown
function test_ClickButton()
{
var notSavedText = "Not saved"
var savedText = "Saved!"
var image = grabImage(myWindowTest);
image.save("something.png");
console.log("step 1")
verify(myWindowTest.saveStatus === notSavedText, "Save status failed!")
console.log("sending click")
mouseClick(myWindowTest.saveButton)
console.log("step 2")
verify(myWindowTest.saveStatus === savedText, "Save status failed!")
}
}
}

Answer 2

thank you all for the leads, indeed the "waitForRendering" resolved the issue
function test_ClickButton()
{
var notSavedText = "Not saved"
var savedText = "Saved!"
console.log("step 1")
verify(myWindowTest.saveStatus === notSavedText, "Save status failed!")
console.log("sending click")
mouseClick(myWindowTest.saveButton)
console.log("step 2")
verify(myWindowTest.saveStatus === savedText, "Save status failed!")
myWindowTest.grabToImage(function(result) {
console.log(result)
result.saveToFile("scrshot.png");
});
**waitForRendering(myWindowTest, 100)**
}