rendering: extract default native scene backend

tests/Rendering/unit/test_camera_scene_renderer.cpp

@@ -4833,6 +4833,55 @@ TEST(
     Pipelines::ClearManagedRenderPipelineBridge();
 }
 
+TEST(
+    DefaultNativeSceneBackend_Test,
+    ReusesBuiltinForwardFeaturesWithoutInstallingFallbackStandalonePasses) {
+    std::unique_ptr<SceneDrawBackend> sceneDrawBackend =
+        Internal::CreateDefaultSceneDrawBackend();
+    ASSERT_NE(sceneDrawBackend, nullptr);
+
+    SceneRenderFeatureHost* const featureHost =
+        sceneDrawBackend->GetSceneFeatureHost();
+    ASSERT_NE(featureHost, nullptr);
+    EXPECT_EQ(featureHost->GetFeaturePassCount(), 2u);
+
+    auto* pipeline =
+        dynamic_cast<RenderPipeline*>(sceneDrawBackend.get());
+    ASSERT_NE(pipeline, nullptr);
+    EXPECT_EQ(
+        pipeline->GetCameraFrameStandalonePass(CameraFrameStage::DepthOnly),
+        nullptr);
+    EXPECT_EQ(
+        pipeline->GetCameraFrameStandalonePass(CameraFrameStage::ShadowCaster),
+        nullptr);
+}
+
+TEST(
+    DefaultPipelineBackendAsset_Test,
+    CreatesFallbackPipelineWithSameDefaultNativeFeatureHost) {
+    const std::shared_ptr<const RenderPipelineAsset> backendAsset =
+        Internal::CreateDefaultPipelineBackendAsset();
+    ASSERT_NE(backendAsset, nullptr);
+
+    std::unique_ptr<RenderPipeline> pipeline = backendAsset->CreatePipeline();
+    ASSERT_NE(pipeline, nullptr);
+
+    auto* sceneDrawBackend =
+        dynamic_cast<SceneDrawBackend*>(pipeline.get());
+    ASSERT_NE(sceneDrawBackend, nullptr);
+    SceneRenderFeatureHost* const featureHost =
+        sceneDrawBackend->GetSceneFeatureHost();
+    ASSERT_NE(featureHost, nullptr);
+    EXPECT_EQ(featureHost->GetFeaturePassCount(), 2u);
+
+    EXPECT_NE(
+        pipeline->GetCameraFrameStandalonePass(CameraFrameStage::DepthOnly),
+        nullptr);
+    EXPECT_NE(
+        pipeline->GetCameraFrameStandalonePass(CameraFrameStage::ShadowCaster),
+        nullptr);
+}
+
 TEST(ManagedScriptableRenderPipelineAsset_Test, LetsManagedBridgeConfigureCameraRenderRequests) {
     Pipelines::ClearManagedRenderPipelineBridge();