feat: add runtime play tick and play-mode scene editing semantics

tests/editor/test_play_session_controller.cpp

@@ -0,0 +1,83 @@
+#include <gtest/gtest.h>
+
+#include "Core/EditorContext.h"
+#include "Core/EditorEvents.h"
+#include "Core/PlaySessionController.h"
+
+#include <XCEngine/Core/Math/Vector3.h>
+
+namespace XCEngine::Editor {
+namespace {
+
+class PlaySessionControllerTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        m_context.GetSceneManager().NewScene("Play Session Scene");
+    }
+
+    EditorContext m_context;
+    PlaySessionController m_controller;
+};
+
+TEST_F(PlaySessionControllerTest, StartPlayClonesCurrentSceneAndStopRestoresEditorScene) {
+    auto* editorEntity = m_context.GetSceneManager().CreateEntity("Persistent");
+    ASSERT_NE(editorEntity, nullptr);
+    const uint64_t editorEntityId = editorEntity->GetID();
+    editorEntity->GetTransform()->SetLocalPosition(Math::Vector3(1.0f, 2.0f, 3.0f));
+
+    int startedCount = 0;
+    int stoppedCount = 0;
+    const uint64_t startedSubscription = m_context.GetEventBus().Subscribe<PlayModeStartedEvent>(
+        [&](const PlayModeStartedEvent&) {
+            ++startedCount;
+        });
+    const uint64_t stoppedSubscription = m_context.GetEventBus().Subscribe<PlayModeStoppedEvent>(
+        [&](const PlayModeStoppedEvent&) {
+            ++stoppedCount;
+        });
+
+    ASSERT_TRUE(m_controller.StartPlay(m_context));
+    EXPECT_EQ(m_context.GetRuntimeMode(), EditorRuntimeMode::Play);
+    EXPECT_EQ(startedCount, 1);
+
+    auto* runtimeEntity = m_context.GetSceneManager().GetEntity(editorEntityId);
+    ASSERT_NE(runtimeEntity, nullptr);
+    runtimeEntity->GetTransform()->SetLocalPosition(Math::Vector3(8.0f, 9.0f, 10.0f));
+    auto* runtimeOnlyEntity = m_context.GetSceneManager().CreateEntity("RuntimeOnly");
+    ASSERT_NE(runtimeOnlyEntity, nullptr);
+    const uint64_t runtimeOnlyId = runtimeOnlyEntity->GetID();
+
+    ASSERT_TRUE(m_controller.StopPlay(m_context));
+    EXPECT_EQ(m_context.GetRuntimeMode(), EditorRuntimeMode::Edit);
+    EXPECT_EQ(stoppedCount, 1);
+
+    auto* restoredEntity = m_context.GetSceneManager().GetEntity(editorEntityId);
+    ASSERT_NE(restoredEntity, nullptr);
+    EXPECT_EQ(m_context.GetSceneManager().GetEntity(runtimeOnlyId), nullptr);
+
+    const Math::Vector3 restoredPosition = restoredEntity->GetTransform()->GetLocalPosition();
+    EXPECT_NEAR(restoredPosition.x, 1.0f, 1e-4f);
+    EXPECT_NEAR(restoredPosition.y, 2.0f, 1e-4f);
+    EXPECT_NEAR(restoredPosition.z, 3.0f, 1e-4f);
+
+    m_context.GetEventBus().Unsubscribe<PlayModeStartedEvent>(startedSubscription);
+    m_context.GetEventBus().Unsubscribe<PlayModeStoppedEvent>(stoppedSubscription);
+}
+
+TEST_F(PlaySessionControllerTest, StartAndStopRequestsRouteThroughEventBus) {
+    auto* editorEntity = m_context.GetSceneManager().CreateEntity("Persistent");
+    ASSERT_NE(editorEntity, nullptr);
+
+    m_controller.Attach(m_context);
+
+    m_context.GetEventBus().Publish(PlayModeStartRequestedEvent{});
+    EXPECT_EQ(m_context.GetRuntimeMode(), EditorRuntimeMode::Play);
+
+    m_context.GetEventBus().Publish(PlayModeStopRequestedEvent{});
+    EXPECT_EQ(m_context.GetRuntimeMode(), EditorRuntimeMode::Edit);
+
+    m_controller.Detach(m_context);
+}
+
+} // namespace
+} // namespace XCEngine::Editor