feat: add vertices instead of deleting all old ones

Author: merydian

ORStools/gui/ORStoolsDialog.py

@@ -793,8 +793,6 @@ def load_vertices_from_layer(self, testing: str = "") -> None:
         if result == QMessageBox.StandardButton.Ok:
             layer = box.selectedLayer()
             try:
-                self.routing_fromline_list.clear()
-
                 for id, feat in enumerate(layer.getFeatures()):
                     geom = feat.geometry()
                     if not geom:

tests/test_gui.py

@@ -782,9 +782,9 @@ def test_load_layer_replaces_existing_vertices(self):
         dialog_main.dlg.load_vertices_from_layer("ok")
 
         # Verify old vertices were cleared
-        self.assertEqual(dialog_main.dlg.routing_fromline_list.count(), 1)
+        self.assertEqual(dialog_main.dlg.routing_fromline_list.count(), 3)
         self.assertEqual(
-            dialog_main.dlg.routing_fromline_list.item(0).text(), "Point 0: 5.000000, 5.000000"
+            dialog_main.dlg.routing_fromline_list.item(2).text(), "Point 2: 5.000000, 5.000000"
         )
 
     def test_load_layer_creates_annotations(self):