Clean up gaussian splat test runtime roots

tests/Rendering/unit/test_render_resource_cache.cpp

@@ -15,6 +15,7 @@
 #include <fstream>
 #include <memory>
 #include <string>
+#include <system_error>
 #include <vector>
 
 using namespace XCEngine::Math;
@@ -402,9 +403,28 @@ GaussianSplat BuildSampleGaussianSplat(const char* artifactPath) {
     return gaussianSplat;
 }
 
-std::filesystem::path CreateTestProjectRoot(const char* folderName) {
-    return std::filesystem::current_path() / "__xc_gaussian_splat_cache_test_runtime" / folderName;
-}
+class ScopedTestProjectRoot final {
+public:
+    explicit ScopedTestProjectRoot(const char* folderName)
+        : m_runtimeRoot(std::filesystem::temp_directory_path() / "xcengine_gaussian_splat_cache_test_runtime")
+        , m_projectRoot(m_runtimeRoot / folderName) {
+        std::error_code ec;
+        std::filesystem::remove_all(m_projectRoot, ec);
+    }
+
+    ~ScopedTestProjectRoot() {
+        std::error_code ec;
+        std::filesystem::remove_all(m_runtimeRoot, ec);
+    }
+
+    const std::filesystem::path& GetPath() const {
+        return m_projectRoot;
+    }
+
+private:
+    std::filesystem::path m_runtimeRoot;
+    std::filesystem::path m_projectRoot;
+};
 
 TEST(RenderResourceCacheTest, GetOrCreateGaussianSplatUploadsStructuredSectionsAndReusesEntry) {
     GaussianSplat gaussianSplat = BuildSampleGaussianSplat("sample.xcgsplat");
@@ -507,7 +527,8 @@ TEST(RenderResourceCacheTest, GetOrCreateGaussianSplatSupportsArtifactRuntimeLoa
 TEST(RenderResourceCacheTest, GetOrCreateGaussianSplatSupportsSourceAssetImportPath) {
     namespace fs = std::filesystem;
 
-    const fs::path projectRoot = CreateTestProjectRoot("source_asset_import");
+    const ScopedTestProjectRoot testProjectRoot("source_asset_import");
+    const fs::path projectRoot = testProjectRoot.GetPath();
     const fs::path assetsDir = projectRoot / "Assets";
     const fs::path sourcePath = assetsDir / "sample.ply";