Stubbing XHRs in QUnit with SinonJS Fake Server

example.js

QUnit.module("my-module",
{
  setup: function () {
    // Configure Sinon's FakeServer instance.  `autoRespond` ensures that any incoming requests
    // will automatically be replied to, otherwise you *must* invoke `this.server.respond` to
    // start processing.
    this.server = sinon.fakeServer.create();
    this.server.autoRespond = true;

    // Tells the FakeServer's XHR request factory that we don't want to respond to every
    // request (ie: some requests should be allowed to pass through unmodified)
    this.server.xhr.useFilters = true;

    var requestUrisOrRegexes = this.requestUrisOrRegexes = [];

    // Add an XHR filter which looks at for any matching URIs which were added using `this.stubXhrRequest`.
    this.server.xhr.addFilter(function (method, uri) {
      var matched = false;

      // Deal with the fact `this.stubRequest` accepts both a string and a regex.
      function isMatch (matcher) {
          return (typeof matcher === "string") ? matcher === uri : matcher.exec(uri) !== null;
      }

      // Check all matchers to see if one matches the incoming URI.
      for (var i = 0; i < requestUrisOrRegexes.length; i++) {
          matched = isMatch(requestUrisOrRegexes[i]);
          if (matched) break;
      }

      // Sinon FakeXHR filters need to return `false` if the request should be stubbed and
      // `true` if it should be allowed to pass through.
      return !matched;
    });
  },

  teardown: function () {
      this.server.restore();
  },

  // Return a pre-canned response object for a given URI.
  stubXhrRequest: function (uriOrRegex, responseObject) {
    // Store the uriOrRegex value so the FakeXHR filter can indicate this request
    // should be faked.
    this.requestUrisOrRegexes.push(uriOrRegex);

    var responseCode = 200;
    var responseHeaders = { "Content-Type": "application/json" };
    var responseBody = JSON.stringify(responseObject);

    this.server.respondWith(uriOrRegex,
        [ responseCode, responseHeaders, responseBody ]
    );
  }
});

QUnit.asyncTest("When a request to `/foo/bar` is made, the `id` should be extracted from the response", function (assert) {
  var expectedId = 303;

  // First arg is a regex or a string which will be used to determine if the supplied response
  // should be served.  Second argument is an Object which will be marshalled into JSON by the
  // `stubXhrRequest` method.
  this.stubXhrRequest(/^\/foo\/bar/, { id: expectedId, body: "hello world!" });

  // Kick off our example integration test.
  myModule.getId("/foo/bar", function (id) {
    // Example assertion assuming `myModule.getId` will invoke this callback when the XHR compeltes.
    assert.equal(id, expectedId, "id was extracted from the response object");

    // Complete this async test.
    QUnit.start();
  });
});