Testing an AJAX function with xhr-mock fails

问题:

I'm trying to test the following function from my network.js:

export function post (data) {
  return new Promise(function (resolve, reject) {
    // need to log to the root
    var url = window.location.protocol + '//' + window.location.hostname
    var xhr = new XMLHttpRequest()

    xhr.onreadystatechange = () => {
      if (xhr.readyState === XMLHttpRequest.DONE) {
        if (xhr.status === 204) {
          resolve(null)
        } else {
          reject(new Error('an error ocurred whilst sending the request'))
        }
      }
    }

    xhr.open('POST', url, true)
    xhr.setRequestHeader('Content-type', 'application/json')
    xhr.send(JSON.stringify(data))
  })
}

My test case looks like this:

import xhrMock from 'xhr-mock'
import * as network from '../src/network'

describe('Payload networking test suite', function () {
  beforeEach(() => xhrMock.setup())

  afterEach(() => xhrMock.teardown())

  test('POSTs JSON string', async () => {
    expect.assertions(1)

    xhrMock.post(window.location.protocol + '//' + window.location.hostname, (req, res) => {
      expect(req.header('Content-Type')).toEqual('application/json')
      return res.status(204)
    })

    await network.post({})
  })
})

When running my test suite I'm getting:

xhr-mock: No handler returned a response for the request.

  POST http://localhost/ HTTP/1.1
  content-type: application/json

  {}

This is mostly based on the documentation and I don't understand why its failing

回答1:

Solution

add a trailing / to the url you are giving xhrMock.post()

Error Details

The url is http://localhost.

That turns into a req.url() of

{
  protocol: 'http',
  host: 'localhost',
  path: '/',
  query: {}
}

Calling toString() on that object returns 'http://localhost/'

xhr-mock compares the URLs by doing req.url().toString() === url

'http://localhost/' === 'http://localhost' returns false so xhr-mock is returning an error that no handler returned a response.

回答2:

I found I had some problems as well and using the following module was a better alternative for me:

https://github.com/berniegp/mock-xmlhttprequest

Usage is pretty straight forward:

const MockXMLHttpRequest = require('mock-xmlhttprequest');
const MockXhr = MockXMLHttpRequest.newMockXhr();

// Mock JSON response
MockXhr.onSend = (xhr) => {
  const responseHeaders = { 'Content-Type': 'application/json' };
  const response = '{ "message": "Success!" }';
  xhr.respond(200, responseHeaders, response);
};

// Install in the global context so "new XMLHttpRequest()" uses the XMLHttpRequest mock
global.XMLHttpRequest = MockXhr;