Unsolved Test PyQt5 GUI Headless on Windows for GitLab CI/CD

[adamhendry]

I can run PyQt5 headless by setting the environment variable

QT_QPA_PLATFORM=offscreen

However, I'm not able to pass my test that a tooltip message appears when hovering over a toolbar button. I know this to work because the test passes when I run it in windowed mode:

def test_toolbar_statusbar_and_tooltip_messages(app: MainApp, qtbot: QtBot) -> None:
    """Test for correct status bar message when a toolbar item is hovered.

    For example, when the user clicks 'File' in the menubar and hovers over 'New', the
    statusbar tooltip should read 'Create a new project...'.

    Args:
        app (MainApp): (fixture) Qt main application
        qtbot (QtBot): (fixture) Bot that imitates user interaction
    """
    # Arrange
    window = app.view

    statusbar = window.statusbar
    toolbar = window.toolbar
    new_action = window.new_action

    new_rect = toolbar.actionGeometry(new_action)
    tooltip = QtWidgets.QToolTip

    # Assert - Precondition
    assert statusbar.currentMessage() == ''
    assert tooltip.text() == ''

    # Act
    qtbot.mouseMove(toolbar, new_rect.center())

    # Assert - Postcondition
    def check_status():
        assert statusbar.currentMessage() == 'Create a new project...'

    def check_tooltip():
        assert tooltip.text() == 'New Project'

    qtbot.waitUntil(check_status)
    qtbot.waitUntil(check_tooltip)

Is there a way to test this in headless mode?