tests: Destroy Qt objects left behind by GUI tests - #1548
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By the time a GUI test is over, pytest-qt has called `close()` and `deleteLater()` on every widget registered with `qtbot.addWidget()`, and has run `processEvents()` a few times. That is not enough to actually destroy them: * `deleteLater()` merely posts a DeferredDelete event, and Qt delivers those only from within a running event loop. There is none at teardown time, so the deletions pile up unprocessed. * The widgets that the application creates without a parent, such as `MainWindow.file_dialog` or the various `Alert` dialogs, are not registered with pytest-qt in the first place. The result is that a Qt test leaves roughly a dozen live widgets behind, and since pytest holds on to the fixtures that reference them for the whole session, they are only ever destroyed by the interpreter's final garbage collection pass -- in an order that PySide does not control, and possibly after the QApplication itself is gone. On Windows this occasionally faults *after* pytest has already reported the test as passed, which fails the CI run with no indication of which test process died. So we destroy them here instead, while the QApplication is still alive and we are still in control of the ordering. Refs #493 Closes #1547
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By the time a GUI test is over, pytest-qt has called
close()anddeleteLater()on every widget registered withqtbot.addWidget(), and has runprocessEvents()a few times. That is not enough to actually destroy them:deleteLater()merely posts a DeferredDelete event, and Qt delivers those only from within a running event loop. There is none at teardown time, so the deletions pile up unprocessed.MainWindow.file_dialogor the variousAlertdialogs, are not registered with pytest-qt in the first place.The result is that a Qt test leaves roughly a dozen live widgets behind, and since pytest holds on to the fixtures that reference them for the whole session, they are only ever destroyed by the interpreter's final garbage collection pass -- in an order that PySide does not control, and possibly after the QApplication itself is gone. On Windows this occasionally faults after pytest has already reported the test as passed, which fails the CI run with no indication of which test process died.
So we destroy them here instead, while the QApplication is still alive and we are still in control of the ordering.
Refs #493
Closes #1547