如何使用 jest 测试 Nest js 中的异步函数

Question

我用我的新框架 Nest js 做了一个简单的测试，但是第一次运行命令 npm run test 我收到此错误

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\xe2\x97\x8f  Cannot log after tests are done. Did you forget to wait for something async in your test?\n    Attempted to log "SUCCESS conection to MEMCACHED server".\n\n      21 |   // this function Stores a new value in Memcached.\n      22 |   setKey(key : string, value : string , timeExp:number) : Promise<boolean>{\n    > 23 |     // Transform the callback into a promise to be used in the controller\n         |                 ^\n      24 |     return new Promise((resolve,reject) =>{\n      25 |       // Using memcached api to set a key\n      26 |       memcached.set(key, value, timeExp, async function (err) {\n\n      at BufferedConsole.log (../node_modules/@jest/console/build/BufferedConsole.js:201:10)\n      at modules/cache/application/cache.service.ts:23:17\n      at allocate (../node_modules/jackpot/index.js:125:5)\n      at Socket.either (../node_modules/jackpot/index.js:166:5)\n

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但这是我的测试文件

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describe('Cache Controller', () => {\n  let controller: CacheController;\n\n  beforeEach(async () => {\n    const module: TestingModule = await Test.createTestingModule({\n      controllers: [CacheController],\n    }).compile();\n\n    controller = module.get<CacheController>(CacheController);\n  });\n\n  it('should be defined', () => {\n    expect(controller).toBeDefined();\n  });\n});\n\n

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• 这是出现错误的函数（如果我不测试这个函数，不知道为什么）
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// this function Stores a new value in Memcached.\n  async setKey(key : string, value : string , timeExp:number) : Promise<boolean>{\n    // Transform the callback into a promise to be used in the controller\n    return await new Promise((resolve,reject) =>{\n      // Using memcached api to set a key\n      memcached.set(key, value, timeExp, function (err) {\n        if (err) return reject(err);\n        resolve(true)\n      });  \n    });\n  }\n

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Answer 1

您的异步函数将返回一个承诺。

将测试用例定义为异步函数并调用await 等待返回值。

it('Test case name', async () => {
   // Await something
   // Expect something
})