如何模拟异步函数的返回值?

时间:2019-01-22 11:13:07

标签: javascript node.js unit-testing ecmascript-6 sinon

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

我尝试了this,但没有成功,我一直从外部API获取数据。

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:

因此,我尝试按照答案之一的建议使用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();
        });

    })
});

2 个答案:

答案 0 :(得分:1)

在源文件中,soapRequest变量本身是一个函数,不是命名的导入(对象),因此不可能仅依靠sinon.stub

如果看一下easy-soap-request源代码,很明显,它会导出函数https://github.com/circa10a/easy-soap-request/blob/master/index.js#L14

根据我的经验,在这种情况下,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
    })
});

如果您不想使用sinon,也可以这样做

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

参考:

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

希望有帮助

答案 1 :(得分:0)

<罢工> 这样做:

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

Documentation

更新:

我不好!我对这个问题不太了解。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。因此,我添加了一个新的文件来请求肥皂。然后,取消测试请求变得容易。

soap-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