Prevent map from panning to first layer's extent upon processing events

CHANGELOG.md

@@ -3,7 +3,7 @@
 ## Fixes
 
 * [#53](https://github.com/GispoCoding/pytest-qgis/pull/53) Allow using MagicMocks to mock layers without problems
-* [#62](https://github.com/GispoCoding/pytest-qgis/pull/62) Allow changing the map extent properly when showing the map
+* [#62](https://github.com/GispoCoding/pytest-qgis/pull/62) Map does no longer zoom to the first added layer upon processing the events when using `qgis_show_map` marker
 
 # Version 2.0.0 (29-11-2023)
 

src/pytest_qgis/pytest_qgis.py

@@ -158,6 +158,7 @@ def qgis_app(request: "SubRequest") -> QgsApplication:
 
     if not request.config._plugin_settings.qgis_init_disabled:
         assert _APP
+        QgsProject.instance().legendLayersAdded.disconnect(_APP.processEvents)
         if not sip.isdeleted(_CANVAS) and _CANVAS is not None:
             _CANVAS.deleteLater()
         _APP.exitQgis()
@@ -303,6 +304,16 @@ def _start_and_configure_qgis_app(config: "Config") -> None:
 
         mock.patch("qgis.utils.iface", _IFACE).start()
 
+    if _APP is not None:
+        # QGIS zooms to the layer's extent if it
+        # is the first layer added to the map.
+        # If the qgis_show_map marker is used, this zooming might occur
+        # at some later time when events are processed (e.g. at qtbot.wait call)
+        # and this might change the extent unexpectedly.
+        # It is better to process events right after adding the
+        # layer to avoid these kind of problems.
+        QgsProject.instance().legendLayersAdded.connect(_APP.processEvents)
+
 
 def _initialize_processing(qgis_app: QgsApplication) -> None:
     python_plugins_path = os.path.join(qgis_app.pkgDataPath(), "python", "plugins")
@@ -317,11 +328,6 @@ def _show_qgis_dlg(common_settings: Settings, qgis_parent: QWidget) -> None:
     if not common_settings.qgis_init_disabled:
         qgis_parent.setWindowTitle("Test QGIS dialog opened by Pytest-qgis")
         qgis_parent.show()
-
-        # Process events each time layer a visible layer is added to
-        # be able to change the extent properly
-        assert _APP
-        QgsProject.instance().legendLayersAdded.connect(_APP.processEvents)
     elif common_settings.qgis_init_disabled:
         warnings.warn(
             "Cannot show QGIS map because QGIS is not initialized. "

tests/visual/test_show_map.py

@@ -129,12 +129,16 @@ def test_show_map_crs_change_to_4326_2(layer_polygon, layer_points, layer_polygo
 
 
 @pytest.mark.qgis_show_map(timeout=DEFAULT_TIMEOUT, zoom_to_common_extent=False)
-def test_show_map_should_not_keep_the_set_extent(
+def test_map_extent_should_not_change_to_layers_extent_when_processing_events(
     layer_polygon_3067, qgis_canvas, qgis_app
 ):
+    extent_smaller_than_layer = QgsRectangle(475804, 7145949.5, 549226, 7219371.5)
+
     QgsProject.instance().addMapLayer(layer_polygon_3067)
-    qgis_canvas.setExtent(QgsRectangle(475804, 7145949.5, 549226, 7219371.5))
+    qgis_canvas.setExtent(extent_smaller_than_layer)
+
     # This triggers the map to set the extent based on the layer
     # if events are not processed after adding the layer
     qgis_app.processEvents()
-    assert qgis_canvas.extent().area() < 1e11  # noqa: PLR2004
+
+    assert qgis_canvas.extent().height() == extent_smaller_than_layer.height()