Prepare script lifecycle and data layer

tests/Scene/test_scene.cpp

@@ -27,9 +27,22 @@ public:
 
     bool m_awakeCalled = false;
     bool m_updateCalled = false;
+    bool m_onDestroyCalled = false;
+    int m_startCount = 0;
+    int m_updateCount = 0;
+    int m_onDestroyCount = 0;
+    int* m_externalOnDestroyCount = nullptr;
 
     void Awake() override { m_awakeCalled = true; }
-    void Update(float deltaTime) override { m_updateCalled = true; }
+    void Start() override { ++m_startCount; }
+    void Update(float deltaTime) override { m_updateCalled = true; ++m_updateCount; }
+    void OnDestroy() override {
+        m_onDestroyCalled = true;
+        ++m_onDestroyCount;
+        if (m_externalOnDestroyCount) {
+            ++(*m_externalOnDestroyCount);
+        }
+    }
 
 private:
     std::string m_customName;
@@ -111,6 +124,17 @@ TEST_F(SceneTest, DestroyGameObject_WithChildren) {
     EXPECT_EQ(testScene->Find("Child"), nullptr);
 }
 
+TEST_F(SceneTest, DestroyGameObject_CallsOnDestroyOnce) {
+    GameObject* go = testScene->CreateGameObject("DestroyMe");
+    TestComponent* comp = go->AddComponent<TestComponent>();
+    int destroyCount = 0;
+    comp->m_externalOnDestroyCount = &destroyCount;
+
+    testScene->DestroyGameObject(go);
+
+    EXPECT_EQ(destroyCount, 1);
+}
+
 TEST_F(SceneTest, Find_Exists) {
     testScene->CreateGameObject("FindMe");
     
@@ -163,6 +187,28 @@ TEST_F(SceneTest, Update_SkipsInactiveObjects) {
     EXPECT_FALSE(comp->m_updateCalled);
 }
 
+TEST_F(SceneTest, Update_RecursivelyUpdatesChildObjects) {
+    GameObject* parent = testScene->CreateGameObject("Parent");
+    GameObject* child = testScene->CreateGameObject("Child", parent);
+    TestComponent* comp = child->AddComponent<TestComponent>();
+
+    testScene->Update(0.016f);
+
+    EXPECT_TRUE(comp->m_updateCalled);
+    EXPECT_EQ(comp->m_updateCount, 1);
+}
+
+TEST_F(SceneTest, Update_CallsStartOnlyOnceBeforeUpdate) {
+    GameObject* go = testScene->CreateGameObject("TestObject");
+    TestComponent* comp = go->AddComponent<TestComponent>();
+
+    testScene->Update(0.016f);
+    testScene->Update(0.016f);
+
+    EXPECT_EQ(comp->m_startCount, 1);
+    EXPECT_EQ(comp->m_updateCount, 2);
+}
+
 TEST(Scene_Test, IsActive_DefaultTrue) {
     Scene s;
     
@@ -415,6 +461,27 @@ TEST_F(SceneTest, SerializeToString_And_DeserializeFromString_PreservesHierarchy
     EXPECT_TRUE(loadedCamera->IsPrimary());
 }
 
+TEST_F(SceneTest, SerializeToString_And_DeserializeFromString_PreservesUUIDs) {
+    GameObject* parent = testScene->CreateGameObject("Parent");
+    GameObject* child = testScene->CreateGameObject("Child", parent);
+
+    const uint64_t parentUUID = parent->GetUUID();
+    const uint64_t childUUID = child->GetUUID();
+
+    const std::string serialized = testScene->SerializeToString();
+
+    Scene loadedScene;
+    loadedScene.DeserializeFromString(serialized);
+
+    GameObject* loadedParent = loadedScene.Find("Parent");
+    GameObject* loadedChild = loadedScene.Find("Child");
+    ASSERT_NE(loadedParent, nullptr);
+    ASSERT_NE(loadedChild, nullptr);
+
+    EXPECT_EQ(loadedParent->GetUUID(), parentUUID);
+    EXPECT_EQ(loadedChild->GetUUID(), childUUID);
+}
+
 TEST_F(SceneTest, Save_ContainsHierarchyAndComponentEntries) {
     GameObject* parent = testScene->CreateGameObject("Parent");
     GameObject* child = testScene->CreateGameObject("Child", parent);