chore: import upstream snapshot with attribution

packages/variable-engine/variable-layout/__tests__/variable-free-layout-transform-empty.test.ts

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
+ * SPDX-License-Identifier: MIT
+ */
+
+import { test, expect } from 'vitest';
+
+import { ScopeChainTransformService } from '../src';
+import { runFreeLayoutTest } from '../__mocks__/run-free-layout-test';
+import { freeLayout1 } from '../__mocks__/free-layout-specs';
+
+runFreeLayoutTest('Variable Free Layout transform empty', freeLayout1, {
+  // 模拟清空作用域
+  transformCovers: () => [],
+  transformDeps: () => [],
+  runExtraTest: (container) => {
+    test('check has transformer', () => {
+      const transformService = container.get(ScopeChainTransformService);
+      expect(transformService.hasTransformer('VARIABLE_LAYOUT_CONFIG')).to.be.true;
+    });
+  },
+});