运行“npm test”时出现以下错误：
\n FAIL __tests__/unit/domain/services/demo-service.ts\n \xe2\x97\x8f Test suite failed to run\n\n TypeError: Jest: a transform must export a `process` function.\n\n at ScriptTransformer._getTransformer (node_modules/@jest/transform/build/ScriptTransformer.js:357:15)\n at ScriptTransformer.transformSource (node_modules/@jest/transform/build/ScriptTransformer.js:419:28)\n at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:523:40)\n at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)\n