Jest报错：SyntaxError: 无法在模块外使用import语句

问题描述 #

已尝试Stack Overflow上编号为58613492、59879689、61781271的解决方案，但运行Jest时仍报错：

SyntaxError: Cannot use import statement outside a module

      1 | import { Lambda, SecretsManager, config as awsConfig } from 'aws-sdk';
    > 2 | import axios from 'axios';

报错仅指向第二行的axios导入语句。当前使用Node.js v14.19.3，相关配置文件如下：

tsconfig.json #

{
  "compilerOptions": {
    "target": "es2017",
    "allowJs": true,
    "module": "commonjs",
    "outDir": "dist",
    "rootDir": ".",
    "importHelpers": true,
    "strict": true,
    "noImplicitReturns": true ,
    "noFallthroughCasesInSwitch": true ,
    "moduleResolution": "node",
    "baseUrl": "./",
    "lib": ["ES2020.Promise"],
    "types": ["node", "jest"],
    "allowSyntheticDefaultImports": true ,
    "esModuleInterop": true,
    "sourceMap": true,
    "experimentalDecorators": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["src"],
  "exclude": ["node_modules"]
}

jest.config.js #

module.exports = {
    preset: "ts-jest",
    transform: {
        "^.+\\.(ts|tsx)?$": "ts-jest",
        "^.+\\.(js|jsx)$": "babel-jest",
    },
    testEnvironment: "node",
    testTimeout: 60000,
    testPathIgnorePatterns: ["dist/*"],
};

babel.config.js #

module.exports = {
    presets: [
        '@babel/preset-typescript',
        [
            '@babel/preset-env',
            {
                targets: { esmodules: false, node: 'current' },
            },
        ],
        '@babel/preset-flow',
    ],
    plugins: [
        ['@babel/plugin-transform-modules-commonjs'],
        ['@babel/plugin-proposal-decorators', { legacy: true }],
        ['@babel/plugin-proposal-class-properties'],
    ],
};

package.json #

{
    "name": "device-job-sender",
    "version": "1.0.0",
    "description": "",
    "main": "src/handlers/job-sender-handler.ts",
    "scripts": {
        "test": "jest --detectOpenHandles",
        "deploy:local": "sls deploy --stage local",
        "start:local": "docker-compose down && docker-compose up -d && npm run deploy:local",
        "deploy": "./.circleci/deploy.sh",
        "prettify": "prettier \"{src,test,scripts}/**/*.{js,ts}\" --write"
    },
    "repository": {
        "type": "git",
        "url": "git+https://github.com/vnatures/device-job-sender.git"
    },
    "author": "",
    "license": "ISC",
    "bugs": {
        "url": "https://github.com/vnatures/device-job-sender/issues"
    },
    "homepage": "https://github.com/vnatures/device-job-sender#readme",
    "devDependencies": {
        "@babel/preset-env": "^7.14.5",
        "@babel/preset-typescript": "^7.14.5",
        "@types/aws-lambda": "^8.10.79",
        "@types/jest": "^26.0.24",
        "@types/redis": "^2.8.29",
        "babel-loader": "^8.2.2",
        "fork-ts-checker-webpack-plugin": "^6.2.12",
        "husky": "^7.0.1",
        "jest": "^26.6.3",
        "ts-jest": "^26.5.6",
        "ts-loader": "^8.1.0",
        "ts-node": "^9.1.1",
        "tsconfig-paths": "^3.9.0",
        "tslib": "^2.3.0",
        "typescript": "^4.2.3",
        "webpack": "^4.44.1",
        "webpack-node-externals": "^2.5.2"
    },
    "dependencies": {
        "@types/aws-iot-device-sdk": "^2.2.3",
        "@vnatures/logger": "^2.0.1",
        "@vnatures/secrets-manager": "^2.0.2",
        "axios": "^1.3.3"
    }
}

解决步骤 #

1. 适配axios版本与Node.js 14兼容性 #

axios 1.3.x默认使用ES模块发布，而Node.js 14对ES模块的处理存在限制。降级axios到兼容CommonJS的版本：

npm install axios@0.27.2

2. 修改Jest配置，强制转换axios模块 #

当前Jest默认跳过node_modules目录的转换，需添加规则让axios被babel-jest处理：

module.exports = {
    preset: "ts-jest",
    transform: {
        "^.+\\.(ts|tsx)?$": "ts-jest",
        "^.+\\.(js|jsx)$": "babel-jest",
    },
    testEnvironment: "node",
    testTimeout: 60000,
    testPathIgnorePatterns: ["dist/*"],
    // 新增：允许转换axios模块
    transformIgnorePatterns: ["node_modules/(?!axios)/"]
};

3. 优化Babel配置，明确模块转换规则 #

调整@babel/preset-env配置，指定Node.js版本并强制转换为CommonJS，移除无用的Flow预设：

module.exports = {
    presets: [
        '@babel/preset-typescript',
        [
            '@babel/preset-env',
            {
                targets: { node: '14.19.3' },
                modules: 'commonjs'
            },
        ]
    ],
    plugins: [
        ['@babel/plugin-transform-modules-commonjs'],
        ['@babel/plugin-proposal-decorators', { legacy: true }],
        ['@babel/plugin-proposal-class-properties'],
    ],
};

4. 确保tsconfig包含测试文件 #

如果测试文件不在src目录下，修改tsconfig的include字段：

"include": ["src", "test"],

内容的提问来源于stack exchange，提问作者Eyal Solomon