core: fix issue #26478 select all instances even in group with mirror'd objects + unit tests

(cherry picked from commit 7d454121de)

src/Gui/Tree.cpp

@@ -5871,7 +5871,7 @@ void DocumentItem::selectAllInstances(const ViewProviderDocumentObject& vpd)
 {
     ViewParentMap parentMap;
     auto pObject = vpd.getObject();
-    if (ObjectMap.find(pObject) == ObjectMap.end()) {
+    if (!ObjectMap.contains(pObject)) {
         return;
     }
 
@@ -5908,7 +5908,9 @@ void DocumentItem::selectAllInstances(const ViewProviderDocumentObject& vpd)
     getTree()->blockSelection(lock);
     if (first) {
         treeWidget()->scrollToItem(first);
-        updateSelection();
+        // updateSelection();  // commented out - it was incorrectly deselecting
+        // ...newly selected items because their qt selection state wasn't
+        // ...yet synchronized when updateItemSelection() checked them
     }
 }
 

src/Mod/Test/CMakeLists.txt

@@ -17,6 +17,7 @@ SET(Test_SRCS
     testmakeWireString.py
     TestPythonSyntax.py
     TestPerf.py
+    TestTreeSelection.py
 )
 
 SET(TestData_SRCS

src/Mod/Test/TestTreeSelection.py

@@ -0,0 +1,253 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+# --------------------------------------------------------------------------
+#                                                                          *
+#    Copyright (c) 2026 Chris Jones github.com/ipatch                      *
+#                                                                          *
+#    This file is part of FreeCAD.                                         *
+#                                                                          *
+#    FreeCAD is free software: you can redistribute it and/or modify it    *
+#    under the terms of the GNU Lesser General Public License as           *
+#    published by the Free Software Foundation, either version 2.1 of the  *
+#    License, or (at your option) any later version.                       *
+#                                                                          *
+#    FreeCAD is distributed in the hope that it will be useful, but        *
+#    WITHOUT ANY WARRANTY; without even the implied warranty of            *
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      *
+#    Lesser General Public License for more details.                       *
+#                                                                          *
+#    You should have received a copy of the GNU Lesser General Public      *
+#    License along with FreeCAD. If not, see                               *
+#    <https://www.gnu.org/licenses/>.                                      *
+#                                                                          *
+# --------------------------------------------------------------------------
+
+"""Unit tests for Tree widget 'Select all instances' functionality.
+
+See GitHub issue #26478.
+- https://github.com/FreeCAD/FreeCAD/issues/26478
+
+To run tests:
+    FreeCAD -t TestTreeSelection.TestSelectAllInstances
+"""
+
+import unittest
+import FreeCAD
+import FreeCADGui
+from FreeCADGui import Selection
+
+import Draft
+
+from PySide6 import QtWidgets
+
+
+class TestSelectAllInstances(unittest.TestCase):
+    """Test cases for 'Select all instances' tree functionality.
+
+    These tests verify that the Std_TreeSelectAllInstances command
+    correctly selects all instances of an object, including those
+    that appear under link-like objects (e.g., Part::Mirroring).
+
+    See GitHub issue #26478.
+    """
+
+    def setUp(self):
+        """Set up test document with objects."""
+        self.doc = FreeCAD.newDocument("TestSelectAllInstances")
+        FreeCADGui.ActiveDocument = FreeCADGui.getDocument(self.doc.Name)
+
+    def tearDown(self):
+        """Clean up test document."""
+        Selection.clearSelection()
+        FreeCAD.closeDocument(self.doc.Name)
+
+    def _get_tree_widget(self):
+        """Get the main tree widget."""
+        mw = FreeCADGui.getMainWindow()
+        for widget in mw.findChildren(QtWidgets.QTreeWidget):
+            if widget.topLevelItemCount() > 0:
+                return widget
+        return None
+
+    def _count_tree_selections_by_name(self, name):
+        """Count how many tree items with given name are selected."""
+        tree = self._get_tree_widget()
+        if not tree:
+            return 0
+        selected = tree.selectedItems()
+        return len([item for item in selected if item.text(0) == name])
+
+    def test_select_all_instances_with_mirror(self):
+        """Test that 'Select all instances' selects objects under Mirror objects.
+
+        test for issue #26478: When an object exists in a Group
+        and is also referenced by Mirror objects, 'Select all instances'
+        should select all instances including those under the Mirror objects.
+        """
+        # Create a Draft Rectangle (matches original Part::Part2DObjectPython)
+        rect = Draft.make_rectangle(10, 10)
+        rect.Label = "Rectangle"
+
+        # Create a group containing the rectangle and mirrors
+        group = self.doc.addObject("App::DocumentObjectGroup", "Group")
+        group.addObject(rect)
+
+        # Create mirror objects that reference the rectangle
+        # Use same naming as original document
+        mirror1 = self.doc.addObject("Part::Mirroring", "Rectangle (mirrored)")
+        mirror1.Source = rect
+        mirror1.Normal = FreeCAD.Vector(1, 0, 0)
+        mirror1.Base = FreeCAD.Vector(20, 0, 0)
+        group.addObject(mirror1)
+
+        mirror2 = self.doc.addObject("Part::Mirroring", "Rectangle (mirrored)001")
+        mirror2.Source = rect
+        mirror2.Normal = FreeCAD.Vector(0, 1, 0)
+        mirror2.Base = FreeCAD.Vector(0, 20, 0)
+        group.addObject(mirror2)
+
+        self.doc.recompute()
+        FreeCADGui.updateGui()
+
+        self._debug_print_document_structure()
+
+        # Get tree widget
+        tree = self._get_tree_widget()
+        self.assertIsNotNone(tree, "Could not find tree widget")
+
+        # Clear any existing selection
+        tree.clearSelection()
+        Selection.clearSelection()
+
+        # Select the rectangle via Gui.Selection (this will select it in the tree)
+        Selection.addSelection(self.doc.Name, rect.Name)
+        FreeCADGui.updateGui()
+
+        # Run the "Select all instances" command
+        FreeCADGui.runCommand("Std_TreeSelectAllInstances", 0)
+        FreeCADGui.updateGui()
+
+        # Count selected Rectangle items in tree
+        count = self._count_tree_selections_by_name("Rectangle")
+
+        # We expect 3 instances:
+        # 1. Rectangle directly in Group
+        # 2. Rectangle under Rectangle (mirrored)
+        # 3. Rectangle under Rectangle (mirrored)001
+        self.assertEqual(
+            count,
+            3,
+            f"Expected 3 'Rectangle' instances selected in tree, got {count}. "
+            f"See GitHub issue #26478.",
+        )
+
+    def test_select_all_instances_with_cuts(self):
+        """Test that 'Select all instances' selects objects used in Part::Cut operations.
+
+        When the same object is used as the Tool in multiple Cut operations,
+        'Select all instances' should select all instances.
+
+        loosely taken from the below freecad wiki page,
+        https://wiki.freecad.org/Std_TreeSelectAllInstances
+        """
+        # Create the shared cube (tool for all cuts)
+        cube = self.doc.addObject("Part::Box", "Cube")
+        cube.Length = 10
+        cube.Width = 10
+        cube.Height = 10
+
+        # Create base shapes
+        cylinder = self.doc.addObject("Part::Cylinder", "Cylinder")
+        cylinder.Radius = 8
+        cylinder.Height = 15
+
+        sphere = self.doc.addObject("Part::Sphere", "Sphere")
+        sphere.Radius = 10
+
+        cone = self.doc.addObject("Part::Cone", "Cone")
+        cone.Radius1 = 10
+        cone.Radius2 = 0
+        cone.Height = 15
+
+        # Create cuts - all using the same Cube as the tool
+        cut1 = self.doc.addObject("Part::Cut", "Cut")
+        cut1.Base = cylinder
+        cut1.Tool = cube
+
+        cut2 = self.doc.addObject("Part::Cut", "Cut001")
+        cut2.Base = sphere
+        cut2.Tool = cube
+
+        cut3 = self.doc.addObject("Part::Cut", "Cut002")
+        cut3.Base = cone
+        cut3.Tool = cube
+
+        self.doc.recompute()
+        FreeCADGui.updateGui()
+
+        self._debug_print_document_structure()
+
+        # Get tree widget
+        tree = self._get_tree_widget()
+        self.assertIsNotNone(tree, "Could not find tree widget")
+
+        # Clear any existing selection
+        tree.clearSelection()
+        Selection.clearSelection()
+
+        # Select the cube
+        Selection.addSelection(self.doc.Name, cube.Name)
+        FreeCADGui.updateGui()
+
+        # Run the "Select all instances" command
+        FreeCADGui.runCommand("Std_TreeSelectAllInstances", 0)
+        FreeCADGui.updateGui()
+
+        # Count selected Cube items in tree
+        count = self._count_tree_selections_by_name("Cube")
+
+        self._debug_print_tree_selection(tree, count)
+
+        # We expect 3 instances:
+        # 1. Cube under Cut
+        # 2. Cube under Cut001
+        # 3. Cube under Cut002
+        self.assertEqual(
+            count,
+            3,
+            f"Expected 3 'Cube' instances selected in tree, got {count}.",
+        )
+
+    def test_select_all_instances_basic(self):
+        """Test basic 'Select all instances' with single object in group."""
+        # Create a simple box
+        box = self.doc.addObject("Part::Box", "Box")
+        box.Length = 10
+        box.Width = 10
+        box.Height = 10
+
+        # Create a group containing the box
+        group = self.doc.addObject("App::DocumentObjectGroup", "Group")
+        group.addObject(box)
+
+        self.doc.recompute()
+        FreeCADGui.updateGui()
+
+        # Get tree widget
+        tree = self._get_tree_widget()
+        self.assertIsNotNone(tree, "Could not find tree widget")
+
+        # Clear and select
+        tree.clearSelection()
+        Selection.clearSelection()
+        Selection.addSelection(self.doc.Name, box.Name)
+        FreeCADGui.updateGui()
+
+        # Run command
+        FreeCADGui.runCommand("Std_TreeSelectAllInstances", 0)
+        FreeCADGui.updateGui()
+
+        # Should have at least 1 selection
+        count = self._count_tree_selections_by_name("Box")
+        self.assertGreaterEqual(
+            count, 1, f"Expected at least 1 'Box' instance selected, got {count}."
+        )