How to grab pointer to popup dialog in Qt which blocks the UI thread in QTest

I'm writing an integration test using QTest in which as soon as I click into the viewport of the widget, a multiline popup QInputDialog appears which blocks the further execution of code and requires manually canceling the dialog. Here is the code:

void PartTest::testTypewriterAnnotTool()
{
    Okular::Part part(nullptr, nullptr, QVariantList()); // It is the main widget of PDF reader comprising of viewport where PDF page is shown

    part.openUrl(QUrl::fromLocalFile(QStringLiteral(KDESRCDIR "data/file1.pdf"))); // open file1.pdf

    part.widget()->show();
    QVERIFY(QTest::qWaitForWindowExposed(part.widget()));

    // Width and height of pageView widget, the child of Part widget which shows the PDF page

    const int width = part.m_pageView->horizontalScrollBar()->maximum() +
                      part.m_pageView->viewport()->width();
    const int height = part.m_pageView->verticalScrollBar()->maximum() +
                       part.m_pageView->viewport()->height();

    part.m_document->setViewportPage(0); // sets viewport page 0, i.e. page number 1

    QMetaObject::invokeMethod(part.m_pageView, "slotToggleAnnotator", Q_ARG( bool, true )); // toggles and shows the annotation toolbar with all tools avaialable

    QList<QToolButton *> toolbuttonList = part.m_pageView->findChildren<QToolButton *>(); // find a list of annotation toolbutton
    // Check if the tooltip of 10th button is "Typewriter"
    QToolButton* typewriterButton = toolbuttonList.at(9);
    QCOMPARE( typewriterButton->toolTip(), QStringLiteral("Typewriter") );

    typewriterButton->click(); // clicking and selecting typewriter annotation tool

    QTest::mouseMove(part.m_pageView->viewport(), QPoint(width * 0.5, height * 0.2)); // leading mouse pointer to a specific point in the viewport

    QTest::mouseClick(part.m_pageView->viewport(), Qt::LeftButton, Qt::NoModifier, QPoint(width * 0.5, height * 0.2)); // mouse left button click on the viewport and a popup dialog with 'add a new note' appears

}

I have to write a test case where I have to grab that popup dialog and programmatically close it. I'm trying to achieve so by using the QTimer where I will execute a function to grab the dialog after 1 second of clicking in the viewport and then trying to close it like this:

class PartTest
{
...
private:
    Okular::part *m_part;
}

void PartTest::testTypewriterAnnotTool()
{
...
    m_part = ∂
    QTimer* mTimer = new QTimer(this);
    mTimer->setSingleShot(true);
    connect(mTimer, SIGNAL(timeout()), SLOT(testDialogClosed()));
    mTimer->start(1000);
    QTest::mouseClick(part.m_pageView->viewport(), Qt::LeftButton, Qt::NoModifier, QPoint(width * 0.5, height * 0.2));
}

void PartTest::testDialogClosed()
{
    bool m_clicked = false;
    QDialog *dialog = m_part->widget()->findChild<QDialog*>();
    if (dialog)
    {
        QDialogButtonBox *buttonBox = dialog->findChild<QDialogButtonBox*>();
        buttonBox->button(QDialogButtonBox::Cancel)->click();
        m_clicked = true;
    }
    QVERIFY(m_clicked);
}

Here, QVERIFY(m_clicked) test case always "fail" that means the popup QInputDialog is not the child of Okular::Part and I'm not getting a way to grab the pointer to this dialog window and close it. Any help?