We get one resizeEvent from QWidget's internal sendPendingMoveAndResizeEvents function and one from QGuiApplication::processExposeEvent(). The second one is sent because we guarantee one resizeEvent prior to any expose event in QWindow.
The test previously passed because we did not allow the event loop to run and the processing of the expose event didn't happen until the test had completed. Any stand alone usecase with a real widget, would have proven the error, however.
I will update the tst_qwidget::resizeEvent() with a couple of QTest::qWaitForWindowExposed() so that the error becomes visible in the test. The test is marked as QSKIP until the problem is resolved.