修复D3D12SwapChain初始化bug并添加单元测试

- 修复Initialize(IDXGIFactory4*, ...)重载缺少m_backBuffers初始化的问题
- 新增test_swap_chain.cpp单元测试文件，包含6个SwapChain测试用例
- 更新unit CMakeLists.txt添加test_swap_chain.cpp和Res路径

engine/src/RHI/D3D12/D3D12SwapChain.cpp

@@ -44,6 +44,13 @@ bool D3D12SwapChain::Initialize(IDXGIFactory4* factory, ID3D12CommandQueue* comm
     m_height = height;
     m_bufferCount = bufferCount;
 
+    m_backBuffers.resize(m_bufferCount);
+    for (uint32_t i = 0; i < m_bufferCount; ++i) {
+        ID3D12Resource* resource = nullptr;
+        m_swapChain->GetBuffer(i, IID_PPV_ARGS(&resource));
+        m_backBuffers[i].InitializeFromExisting(resource);
+    }
+
     return true;
 }
 

tests/RHI/D3D12/unit/CMakeLists.txt

@@ -18,6 +18,7 @@ set(TEST_SOURCES
     test_root_signature.cpp
     test_pipeline_state.cpp
     test_views.cpp
+    test_swap_chain.cpp
 )
 
 add_executable(d3d12_engine_tests ${TEST_SOURCES})
@@ -38,12 +39,12 @@ target_include_directories(d3d12_engine_tests PRIVATE
 )
 
 target_compile_definitions(d3d12_engine_tests PRIVATE
-    TEST_RESOURCES_DIR="${PROJECT_ROOT_DIR}/tests/RHI/D3D12/integration/Res"
+    TEST_RESOURCES_DIR="${PROJECT_ROOT_DIR}/tests/RHI/D3D12/integration/minimal/Res"
 )
 
 add_custom_command(TARGET d3d12_engine_tests POST_BUILD
     COMMAND ${CMAKE_COMMAND} -E copy_directory
-    ${PROJECT_ROOT_DIR}/tests/RHI/D3D12/integration/Res
+    ${PROJECT_ROOT_DIR}/tests/RHI/D3D12/integration/minimal/Res
     $<TARGET_FILE_DIR:d3d12_engine_tests>/Res
 )
 

tests/RHI/D3D12/unit/test_swap_chain.cpp

@@ -0,0 +1,193 @@
+#include "fixtures/D3D12TestFixture.h"
+#include "XCEngine/RHI/D3D12/D3D12SwapChain.h"
+#include <windows.h>
+
+using namespace XCEngine::RHI;
+
+class SwapChainTestFixture : public ::testing::Test {
+protected:
+    void SetUp() override {
+        HRESULT hr = D3D12CreateDevice(
+            nullptr,
+            D3D_FEATURE_LEVEL_12_0,
+            IID_PPV_ARGS(&mDevice)
+        );
+
+        if (FAILED(hr)) {
+            GTEST_SKIP() << "Failed to create D3D12 device";
+            return;
+        }
+
+        D3D12_COMMAND_QUEUE_DESC queueDesc = {};
+        queueDesc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
+
+        hr = mDevice->CreateCommandQueue(&queueDesc, IID_PPV_ARGS(&mCommandQueue));
+        if (FAILED(hr)) {
+            GTEST_SKIP() << "Failed to create command queue";
+            return;
+        }
+
+        hr = CreateDXGIFactory1(IID_PPV_ARGS(&mFactory));
+        if (FAILED(hr)) {
+            GTEST_SKIP() << "Failed to create DXGI factory";
+            return;
+        }
+
+        WNDCLASSEX wc = {};
+        wc.cbSize = sizeof(WNDCLASSEX);
+        wc.lpfnWndProc = DefWindowProc;
+        wc.hInstance = GetModuleHandle(nullptr);
+        wc.lpszClassName = "SwapChainTest";
+        RegisterClassEx(&wc);
+
+        mHWND = CreateWindowEx(
+            0,
+            "SwapChainTest",
+            "SwapChain Test",
+            WS_OVERLAPPEDWINDOW,
+            CW_USEDEFAULT,
+            CW_USEDEFAULT,
+            800,
+            600,
+            NULL,
+            NULL,
+            wc.hInstance,
+            NULL
+        );
+
+        if (!mHWND) {
+            GTEST_SKIP() << "Failed to create window";
+            return;
+        }
+    }
+
+    void TearDown() override {
+        if (mCommandQueue) {
+            WaitForGPU();
+        }
+        if (mHWND) {
+            DestroyWindow(mHWND);
+        }
+        mSwapChain.Shutdown();
+        mCommandQueue.Reset();
+        mDevice.Reset();
+        mFactory.Reset();
+    }
+
+    void WaitForGPU() {
+        if (!mCommandQueue || !mDevice) return;
+
+        ComPtr<ID3D12Fence> fence;
+        UINT64 fenceValue = 1;
+
+        HRESULT hr = mDevice->CreateFence(0, D3D12_FENCE_FLAG_NONE, IID_PPV_ARGS(&fence));
+        if (SUCCEEDED(hr)) {
+            mCommandQueue->Signal(fence.Get(), fenceValue);
+            if (fence->GetCompletedValue() < fenceValue) {
+                HANDLE eventHandle = CreateEvent(nullptr, FALSE, FALSE, nullptr);
+                if (eventHandle) {
+                    fence->SetEventOnCompletion(fenceValue, eventHandle);
+                    WaitForSingleObject(eventHandle, INFINITE);
+                    CloseHandle(eventHandle);
+                }
+            }
+        }
+    }
+
+    Microsoft::WRL::ComPtr<ID3D12Device> mDevice;
+    Microsoft::WRL::ComPtr<ID3D12CommandQueue> mCommandQueue;
+    Microsoft::WRL::ComPtr<IDXGIFactory4> mFactory;
+    HWND mHWND = nullptr;
+    D3D12SwapChain mSwapChain;
+};
+
+TEST_F(SwapChainTestFixture, SwapChain_Initialize_FromFactory) {
+    bool result = mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    );
+
+    ASSERT_TRUE(result);
+}
+
+TEST_F(SwapChainTestFixture, SwapChain_GetBackBuffer_ValidIndex) {
+    ASSERT_TRUE(mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    ));
+
+    D3D12Texture* backBuffer0 = mSwapChain.GetBackBuffer(0);
+    ASSERT_NE(backBuffer0, nullptr);
+
+    D3D12Texture* backBuffer1 = mSwapChain.GetBackBuffer(1);
+    ASSERT_NE(backBuffer1, nullptr);
+
+    ID3D12Resource* resource0 = backBuffer0->GetResource();
+    ID3D12Resource* resource1 = backBuffer1->GetResource();
+    ASSERT_NE(resource0, nullptr);
+    ASSERT_NE(resource1, nullptr);
+
+    ASSERT_NE(resource0, resource1);
+}
+
+TEST_F(SwapChainTestFixture, SwapChain_GetBackBuffer_InvalidIndex) {
+    ASSERT_TRUE(mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    ));
+
+    D3D12Texture* backBuffer = mSwapChain.GetBackBuffer(99);
+    ASSERT_TRUE(backBuffer == nullptr);
+}
+
+TEST_F(SwapChainTestFixture, SwapChain_GetCurrentBackBufferIndex) {
+    ASSERT_TRUE(mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    ));
+
+    uint32_t index = mSwapChain.GetCurrentBackBufferIndex();
+    EXPECT_LT(index, 2u);
+}
+
+TEST_F(SwapChainTestFixture, SwapChain_Present_DoesNotCrash) {
+    ASSERT_TRUE(mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    ));
+
+    ASSERT_NO_FATAL_FAILURE(mSwapChain.Present(0, 0));
+}
+
+TEST_F(SwapChainTestFixture, SwapChain_Shutdown_Cleanup) {
+    ASSERT_TRUE(mSwapChain.Initialize(
+        mFactory.Get(),
+        mCommandQueue.Get(),
+        mHWND,
+        800,
+        600,
+        2
+    ));
+
+    ASSERT_NO_FATAL_FAILURE(mSwapChain.Shutdown());
+}