Avoiding screen setup changed modals twice+ on fast screen changes

openlp/core/ui/mainwindow.py

@@ -1015,13 +1015,13 @@ class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow, LogMixin, RegistryPropert
         # also do not show if the settings window is visible
         if not self.settings_form.isVisible() and not self.screen_change_timestamp or \
                 self.screen_change_timestamp and (datetime.now() - self.screen_change_timestamp).seconds > 5:
+            self.screen_change_timestamp = datetime.now()
             QtWidgets.QMessageBox.warning(self, translate('OpenLP.MainWindow', 'Screen setup has changed'),
                                           translate('OpenLP.MainWindow',
                                                     'The screen setup has changed. '
                                                     'OpenLP will try to automatically select a display screen, but '
                                                     'you should consider updating the screen settings.'),
                                           QtWidgets.QMessageBox.StandardButtons(QtWidgets.QMessageBox.Ok))
-            self.screen_change_timestamp = datetime.now()
 
     def closeEvent(self, event):
         """

tests/openlp_core/ui/test_mainwindow.py

@@ -687,3 +687,46 @@ def test_load_settings_view_mode_live(mocked_view_mode, main_window, settings):
     # THEN:
     # The default mode should have been called.
     mocked_view_mode.assert_called_with(True, True, True, True, False, True)
+
+
+@patch('openlp.core.ui.mainwindow.QtWidgets.QMessageBox.warning')
+def test_screen_changed_modal(mocked_warning, main_window):
+    """
+    Test that the screen changed modal is shown whether a 'config_screen_changed' event is dispatched
+    """
+    # GIVEN: a newly opened OpenLP instance, mocked screens and renderer
+    main_window._live_controller = MagicMock()
+    main_window._preview_controller = MagicMock()
+    main_window._renderer = MagicMock()
+
+    # WHEN: we trigger a 'config_screen_changed' event
+    Registry().execute('config_screen_changed')
+
+    # THEN: The modal should be called once
+    mocked_warning.assert_called_once()
+
+
+@patch('openlp.core.ui.mainwindow.QtWidgets.QMessageBox.warning')
+def test_screen_changed_modal_sets_timestamp_before_blocking_on_modal(mocked_warning, main_window):
+    """
+    Test that the screen changed modal latest shown timestamp is set before showing warning message, so
+    that duplicate modals due to event spamming on 'config_screen_changed' in less than 5 seconds is mitigated.
+    """
+    # GIVEN: a newly opened OpenLP instance, mocked screens, renderer and an special QMessageBox warning handler
+    main_window._live_controller = MagicMock()
+    main_window._preview_controller = MagicMock()
+    main_window._renderer = MagicMock()
+
+    def resets_timestamp(*args, **kwargs):
+        nonlocal main_window
+        main_window.screen_change_timestamp = None
+
+    mocked_warning.side_effect = resets_timestamp
+
+    # WHEN: we trigger a 'config_screen_changed' event
+    Registry().execute('config_screen_changed')
+
+    # THEN: main_window.screen_change_timestamp should be "None", indicating that timestamp is set before
+    # the blocking modal is shown.
+    mocked_warning.assert_called_once()
+    assert main_window.screen_change_timestamp is None