@shackpank/truman/src/helpers/xhr.js

Simple test fixtures for single page apps

'use strict';

let _ = require('lodash');
let RealXMLHttpRequest = XMLHttpRequest;

module.exports = {

  getResponseHeadersObject(xhr) {
    let result = {};
    const headers = xhr.getAllResponseHeaders().split('\n');

    headers.forEach((header) => {
      let headerSegments = header.split(':');
      const key = headerSegments.shift();
      if (key) {
        result[key] = _.trim(headerSegments.join(':'));
      }
    });

    return result;
  },

  getQueryStringObject(xhr, omitted) {
    const parser = document.createElement('a');
    parser.href = xhr.url;

    const qsObj = parser.search.replace(/(^\?)/, '')
      .split('&')
      .map(function(n) {
        n = n.split('=');
        this[n[0]] = n[1];
        return this;
      }.bind({}))[0];

    // Simple workaround for an edge case with the above code.
    if (_.isEqual(qsObj, { '': undefined })) {
      return {};
    }

    return _.omit(qsObj, omitted);
  },

  // WARNING: This function is a bit of a mindfuck. It's essentially making
  // any request data sent to real servers available on the fake XHR that we're
  // inspecting to build our fixtures so we can access/store it. Should probably
  // be done as a much cleaner PR to the Sinon project rather than a hack here.
  monkeyPatchXHR() {
    // 1. Push the fake XHR as a 'password' arg on to calls to 'open'.
    const oldOpen = XMLHttpRequest.prototype.open;
    XMLHttpRequest.prototype.open = function() {
      let args = Array.prototype.slice.call(arguments);

      // Adding as an extra arg breaks jqXHR, so hijack password argument: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest#open()
      while (args.length < 5) {
        args.push(undefined);
      }
      args[args.length - 1] = this;

      return oldOpen.apply(this, args);
    };

    // 2. Intercept the fake XHR argument and add it as a property of the real XHR.
    const oldRealOpen = RealXMLHttpRequest.prototype.open;
    RealXMLHttpRequest.prototype.open = function() {
      let args = Array.prototype.slice.call(arguments);

      if (args[args.length - 1] instanceof XMLHttpRequest) {
        this.originalFakeXHR = args.pop();
      }

      return oldRealOpen.apply(this, args);
    };

    // 3. When send is called on the real XHR, intercept the request data and push it back onto the fake XHR.
    const oldRealSend = RealXMLHttpRequest.prototype.send;
    RealXMLHttpRequest.prototype.send = function(data) {
      if (this.originalFakeXHR) {
        this.originalFakeXHR.requestBody = data;
      }
      return oldRealSend.apply(this, arguments);
    };
  },

  unMonkeyPatchXHR() {
    XMLHttpRequest.prototype.open = RealXMLHttpRequest.prototype.open;
    XMLHttpRequest.prototype.send = RealXMLHttpRequest.prototype.send;
  }

};