diff --git a/src/MaterialComboDelegate_test.cpp b/src/MaterialComboDelegate_test.cpp
index 005996696..333d9e4d7 100644
--- a/src/MaterialComboDelegate_test.cpp
+++ b/src/MaterialComboDelegate_test.cpp
@@ -5,6 +5,7 @@
 #include <QSignalSpy>
 #include <QStandardItemModel>
 #include <QStyleOptionViewItem>
+#include <QMetaObject>
 #include <QThread>
 #include "MaterialComboDelegate.h"
 #include "Manager.h"
@@ -186,3 +187,40 @@ TEST_F(MaterialComboDelegateTest, MaterialColumnWithoutSubEntityProducesEmptySty
 
     EXPECT_TRUE(option.text.isEmpty());
 }
+
+TEST_F(MaterialComboDelegateTest, SetEditorDataForMaterialColumnWithoutSubEntityDoesNotBreakSelection)
+{
+    MaterialComboDelegate delegate;
+    QWidget parentWidget;
+    QStyleOptionViewItem option;
+    QStandardItemModel model(1, 3);
+    QModelIndex index = model.index(0, 2);
+
+    QWidget* editor = delegate.createEditor(&parentWidget, option, index);
+    auto* comboBox = qobject_cast<QComboBox*>(editor);
+    ASSERT_NE(comboBox, nullptr);
+    ASSERT_GT(comboBox->count(), 0);
+
+    comboBox->setCurrentIndex(0);
+    const QString previousText = comboBox->currentText();
+    delegate.setEditorData(editor, index);
+
+    // For non-editable QComboBox, setting an absent text may preserve current selection.
+    EXPECT_TRUE(comboBox->currentText().isEmpty() || comboBox->currentText() == previousText);
+
+    delete editor;
+}
+
+TEST_F(MaterialComboDelegateTest, CommitAndCloseEditorWithoutSenderDoesNotEmitSignals)
+{
+    MaterialComboDelegate delegate;
+    QSignalSpy commitSpy(&delegate, &QAbstractItemDelegate::commitData);
+    QSignalSpy closeSpy(&delegate, &QAbstractItemDelegate::closeEditor);
+    ASSERT_TRUE(commitSpy.isValid());
+    ASSERT_TRUE(closeSpy.isValid());
+
+    ASSERT_TRUE(QMetaObject::invokeMethod(&delegate, "commitAndCloseEditor", Qt::DirectConnection));
+
+    EXPECT_EQ(commitSpy.count(), 0);
+    EXPECT_EQ(closeSpy.count(), 0);
+}
diff --git a/src/SelectionSet_test.cpp b/src/SelectionSet_test.cpp
index 87ec0d0e0..4372e0d18 100644
--- a/src/SelectionSet_test.cpp
+++ b/src/SelectionSet_test.cpp
@@ -819,5 +819,48 @@ TEST_F(SelectionSetTests, RemoveNonExistentEntityAndSubEntityReturnFalse)
     Manager::getSingleton()->destroySceneNode(node);
 }
 
+TEST_F(SelectionSetTests, SingletonKillAndRecreateProducesValidInstance)
+{
+    SelectionSet* first = SelectionSet::getSingleton();
+    ASSERT_NE(first, nullptr);
+
+    SelectionSet::kill();
+
+    SelectionSet* second = SelectionSet::getSingleton();
+    ASSERT_NE(second, nullptr);
+}
+
+TEST_F(SelectionSetTests, GetResolvedEntitiesWithEmptySelectionReturnsEmptyList)
+{
+    SelectionSet* selectionSet = SelectionSet::getSingleton();
+    selectionSet->clear();
+
+    const QList<Ogre::Entity*> resolved = selectionSet->getResolvedEntities();
+    EXPECT_TRUE(resolved.isEmpty());
+}
+
+TEST_F(SelectionSetTests, GetSelectionCenterWithMultipleNodesAveragesPositions)
+{
+    SelectionSet* selectionSet = SelectionSet::getSingleton();
+    selectionSet->clear();
+
+    Ogre::SceneNode* node1 = Manager::getSingleton()->addSceneNode("center_nodes_1");
+    Ogre::SceneNode* node2 = Manager::getSingleton()->addSceneNode("center_nodes_2");
+    ASSERT_NE(node1, nullptr);
+    ASSERT_NE(node2, nullptr);
+
+    node1->setPosition(1.0f, 2.0f, 3.0f);
+    node2->setPosition(5.0f, 6.0f, 7.0f);
+    selectionSet->append(node1);
+    selectionSet->append(node2);
+
+    const Ogre::Vector3 center = selectionSet->getSelectionCenter();
+    EXPECT_EQ(center, Ogre::Vector3(3.0f, 4.0f, 5.0f));
+
+    selectionSet->clear();
+    Manager::getSingleton()->destroySceneNode(node1);
+    Manager::getSingleton()->destroySceneNode(node2);
+}
+
 // NOTE: GetSelectionCenterWithSubEntity and all subsequent tests were removed
 // because they crash in CI (PrimitiveObject::createCube requires GL context).