如何模拟异步函数的 return 值？

Question

我正在尝试测试使用 'easy-soap-request' 库的函数。我想模拟 'soapRequest' 函数返回的结果。

我试过 this 但没用，我一直从外部获取数据 API。

client.js

const soapRequest = require('easy-soap-request');

async function get_data(){
    var response = await soapRequest(url, auth_headers) //this is what I want to mock
    var result;
    result = some_parsing_function(response); //this is what I want test
    return result;
}

test.js

const client = require('../../client');

describe('get_data tests', () =>{
    it('should test sth', function (done) {

        var stubed = stub(client, 'soapRequest').returns('dummy value');

        client.get_data().then((result) => {
            //assertions
            console.log(result) //result still has value from external service
            done();
        });

    })
});

编辑：

所以我尝试按照其中一个答案的建议使用 sinon.fake()。

const client = require('../../client');

describe('get_data tests', () =>{
    it('should test sth', function (done) {

        var fake_soap = fake(async () => {
            return 12345;
        });

        replace(cilent, 'soapRequest', fake_soap);

        client.soapRequest().then((res) => {
            console.log(res); // 12345
        })

        client.get_data().then((result) => {
            //assertions
            console.log(result) //still original value from external service
            done();
        });

    })
});

Answer 1

~~这将做：~~

~~let asyncHandler = sinon.fake(async () => {});~~

~~Documentation~~

更新：

我的错！我没有很好地理解这个问题。这是解决它的一种方法。此外，最好将外部依赖项与应用程序逻辑分开。所以，我添加了一个新文件来发出 soap 请求。然后，对测试请求进行存根变得容易。

肥皂-connector.js

const soapRequest = require('easy-soap-request');
exports.request = async function request(url, auth_headers) {
  return soapRequest(url, auth_headers);
};

client.js

const soapConnector = require('./soap-connector');
async function get_data(){
    var response = await soapConnector.request(url, auth_headers) //this is what I want to mock
    var result;
    result = some_parsing_function(response); //this is what I want test
    return result;
}

test.js

const soapConnector = require('../../soap-connector');
const client = require('../../client');

describe('get_data tests', () =>{
    it('should test sth', function (done) {

        var stubed = stub(soapConnector, 'request').callsFake(async () => {
            return 12345;
        });

        client.get_data().then((result) => {
            //assertions
            console.log(result) //result still has value from external service
            done();
        });

    })
});

Documentation

Answer 2

在源文件中，soapRequest变量本身是一个函数不是命名导入（对象）所以不可能只依赖sinon.stub .

如果看一下easy-soap-request源代码，显然，它导出了一个函数https://github.com/circa10a/easy-soap-request/blob/master/index.js#L14

根据我的经验，对于这种情况，可以通过如下添加proxyquire来解决。

const proxyquire = require('proxyquire');
const sinon = require('sinon');

// we mock `easy-soap-request` (the library name) by using `sinon.stub`
const client = proxyquire('../../client', { 'easy-soap-request': sinon.stub().returns('dummy value') })

describe('get_data tests', () =>{
    it('should test sth', async () => { // use async/await for better code
        const result = await client.get_data();
        console.log(result); // dummy value
    })
});

如果你不想用sinon，你也可以这样做

const client = proxyquire('../../client', { 'easy-soap-request': () => 'dummy value' })

参考：

https://www.npmjs.com/package/proxyquire

希望对您有所帮助

如何模拟异步函数的 return 值？

How to mock return value of async function?

javascript

unit-testing

node.js

sinon

ecmascript-6