首頁猿問無法模擬 Promise 函數

無法模擬 Promise 函數

JavaScript

qq_笑_17 2023-10-20 16:12:06

我有以下 lambda (aws) 代碼：exports.APILambda = (databaseConnection) => { return function (event, context, callback) { context.callbackWaitsForEmptyEventLoop = false const connection = databaseConnection() connection.then((connection, query, args) => { connection.query(queries(query, args), args) .then(result => { console.log(result) connection.end() callback(null, { data: result }) }) .catch(err => { throw err }) }) .catch(err => { logger.error(`${err.stack}`) callback(err) }) }}databaseConnection是一個 mariaDb 連接，實現為：function databaseConnection () { return mariadb.createConnection({ host: process.env.DB_HOST, user: process.env.DB_USER, password: process.env.DB_PASSWORD, port: '3306', database: 'test' })}我的測試是：describe('on new query', () => { it('returns data', async (done) => { await runLambda( ['person', ['John']], (query) => { expect(query).toHaveBeenCalledWith( expect.arrayContaining(['person', ['John']]) ) }, done) })})對于該測試，我必須編寫以下函數：async function runLambda (args, assertions, done) { const query = jest.fn(args => { return Promise.resolve({ 'name': 'John', 'lastName': 'Wayne' }) }) const onNewQuery = APILambda(async () => ({ query })) const event = {} const context = {} await onNewQuery( event, context, (err, result) => { if (err) done(err) assertions(query) done(result) } )}但是當我運行它時我遇到了麻煩，它不斷拋出：TypeError: connection.end is not a function或者說args未定義。有人可以闡明如何正確地嘲笑這一點嗎？

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1 回答

慕仙森

TA貢獻1827條經驗獲得超8個贊

您的代碼存在很多問題：

您應該為connection.end()方法創建模擬。
你不應該將成功的結果傳遞給done()回調
您應該返回一個數組來解析的多個值connection.then()。
你沒有提供queries函數，所以我直接傳遞queryandargs參數。
你傳了args參數，但是你沒有使用它，我下面根據代碼的意思使用它

一個工作示例：

testUtils.js:

const { APILambda } = require('./apiLambda');

// 5. You passed `args` parameter, but you didn't use it, I use it below based on the meaning of code

async function runLambda(args, assertions, done) {

const query = jest.fn(() => {

return Promise.resolve({

name: 'John',

lastName: 'Wayne',

});

// 1. create mock for `connection.end()` method.

const end = jest.fn();

// 3. You should return an array to resolve multiple values for connection.then()

const onNewQuery = APILambda(async () => [{ query, end }, args, null]);

const event = {};

const context = {};

await onNewQuery(event, context, (err, result) => {

if (err) done(err);

assertions(query);

// 2. you should NOT pass successful result to done() callback

done();

});

}

module.exports = { runLambda };

apiLambda.js:

exports.APILambda = (databaseConnection) => {

return function(event, context, callback) {

context.callbackWaitsForEmptyEventLoop = false;

const connection = databaseConnection();

connection

.then(([connection, query, args]) => {

connection

// 4. You didn't provide `queries` function, so I just pass `query` and `args` parameters directly.

.query(query, args)

.then((result) => {

console.log(result);

connection.end();

callback(null, { data: result });

})

.catch((err) => {

throw err;

});

})

.catch((err) => {

console.error(`${err.stack}`);

callback(err);

});

};

apiLambda.test.js:

const { runLambda } = require('./testUtils');

describe('on new query', () => {

it('returns data', async (done) => {

await runLambda(

['person', ['John']],

(query) => {

expect(query).toHaveBeenCalledWith(['person', ['John']], null);

done,

);

});

單元測試結果：

PASS src/stackoverflow/65179710/apiLambda.test.js (9.195s)

on new query

? returns data (16ms)

console.log src/stackoverflow/65179710/apiLambda.js:341

{ name: 'John', lastName: 'Wayne' }

--------------|----------|----------|----------|----------|-------------------|

--------------|----------|----------|----------|----------|-------------------|

All files | 85.19 | 50 | 81.82 | 87.5 | |

apiLambda.js | 75 | 100 | 66.67 | 75 | 18,22,23 |

testUtils.js | 93.33 | 50 | 100 | 100 | 19 |

--------------|----------|----------|----------|----------|-------------------|

Test Suites: 1 passed, 1 total

Tests: 1 passed, 1 total

Snapshots: 0 total

Time: 10.556s

反對回復 2023-10-20

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