diff --git a/selenium/cookies.js b/selenium/cookies.js
index 9335077..8a29f68 100644
--- a/selenium/cookies.js
+++ b/selenium/cookies.js
@@ -1,19 +1,20 @@
 'use strict';
 
-const cookieParser = require('cookie-parser'),
+const express = require('express'),
+  cookieParser = require('cookie-parser'),
   {requestRecorderMiddleware, baseTestApp} = require('./utils');
 
 let fpcookie = {name: '1pname', value: '1pvalue'},
   tpcookie = {name: '3pname', value: '3pvalue'};
 
 
-function cookieSetterApp(cookieName, cookieValue) {
-  let app = requestRecorderMiddleware();
+function cookieSetterApp(cookieName, cookieValue, app = express()) {
   app.use(cookieParser());
   app.use((req, res, next) => {
     res.cookie(cookieName, cookieValue);
     next();
   });
+  requestRecorderMiddleware(app);
   return app;
 }
 
diff --git a/selenium/integration_tests.js b/selenium/integration_tests.js
index 314c1e0..3a8bb86 100644
--- a/selenium/integration_tests.js
+++ b/selenium/integration_tests.js
@@ -7,9 +7,9 @@ const {newDriver, startApp, stopApp, firstPartyHost} = require('./utils'),
   {etagApp} = require('./etags');
 
 describe('etag tests', function() {
-  beforeEach(function() {
+  beforeEach(async function() {
     this.app = etagApp();
-    this.driver = newDriver();
+    this.driver = await newDriver();
     startApp(this.app);
   });
   afterEach(function() {
@@ -18,21 +18,20 @@ describe('etag tests', function() {
   });
   it('blocks etags', async function() {
     let {app, driver} = this;
-    await driver.get('about:blank');
-    await driver.get(firstPartyHost);
-    await driver.get(firstPartyHost);
-    let req1 = await app.firstParty.requests.next();
+    await driver.get(firstPartyHost);  // etag gets set
+    await driver.get(firstPartyHost);  // browser sends if-none-match to check if etag still valid
+    let req = await app.firstParty.requests.next();
     //let req3 = await app.thirdParty.requests.next();
-    assert.isTrue(req1.headers.hasOwnProperty('if-none-match'), 'allows 1st party etags on first visit');
+    assert.isTrue(req.headers.hasOwnProperty('if-none-match'), 'allows 1st party etags on first visit');
     // known failure on chrome due to lack of access to caching headers in chrome webrquest api
     //assert.isFalse(req3.headers.hasOwnProperty('if-none-match'), 'blocks 3rd party etags headers on first visit');
   });
 });
 
 describe('cookie tests', function() {
-  beforeEach(function() {
+  beforeEach(async function() {
     this.app = cookieApp();
-    this.driver = newDriver();
+    this.driver = await newDriver();
     startApp(this.app);
   });
   afterEach(function() {
@@ -42,6 +41,7 @@ describe('cookie tests', function() {
 
   it('blocks cookies', async function() {
     let {app, driver} = this;
+
     await driver.get(firstPartyHost);
     let request = await app.firstParty.requests.next();
     // no cookies initially
diff --git a/selenium/utils.js b/selenium/utils.js
index af9a946..9dc154e 100644
--- a/selenium/utils.js
+++ b/selenium/utils.js
@@ -2,6 +2,7 @@
 
 const sw = require('selenium-webdriver'),
   {createServer} = require('http'),
+  path = require('path'),
   vhost = require('vhost'),
   express = require('express');
 
@@ -10,7 +11,7 @@ function startApp(app, port=PORT) {
   app.server.listen(port);
 }
 
-const path = '../src/.',
+const srcDir = '../src/.',
   PORT = 8000,
   host = (hostname, port) => `${hostname}:${port}`,
   firstPartyHostname = 'firstparty.local',
@@ -33,7 +34,7 @@ function stopApp(app) {
  * 127.0.0.1    thirdparty.local
  */
 
-function loadDriverWithExtension(extPath) {
+async function loadDriverWithExtension(extPath) {
   let chromeOptions = sw.Capabilities.chrome();
   chromeOptions.set("chromeOptions",  {"args": [
     `--load-extension=${extPath}`,
@@ -45,11 +46,13 @@ function loadDriverWithExtension(extPath) {
       .build();
 }
 
-function newDriver() {
-  return loadDriverWithExtension(path);
+async function newDriver() {
+  const srcPath = path.resolve(__dirname, srcDir);
+  return await loadDriverWithExtension(srcPath);
 }
 
 class Channel {
+  // async stack datastructure
   constructor() {
     this.items = [];
     this.waiting = [];
@@ -63,12 +66,16 @@ class Channel {
       });
     }
   }
+
+  // Get the item from the top of the stack, or wait for an item if there are none.
   async next() {
     return await this.popQueue();
   }
+
+  // Push an item onto the stack.
   push(item) {
     if (this.waiting.length > 0) {
-      this.waiting.shift()(item);
+      this.waiting.pop()(item);
     } else {
       this.items.push(item);
     }
@@ -87,7 +94,7 @@ function requestRecorderMiddleware(app = express()) {
 }
 
 function firstPartyApp(app = express(), tpHost = thirdPartyHost) {
-  app.get('/', (req, res) => {
+  app.get('*', (req, res) => {
     return res.send(
       `<script type="text/javascript" src="http://${tpHost}/tracker.js"></script>`
     );
@@ -96,7 +103,7 @@ function firstPartyApp(app = express(), tpHost = thirdPartyHost) {
 }
 
 function thirdPartyApp(app = express()) {
-  app.get('/tracker.js', (req, res) => {
+  app.get('*', (req, res) => {
     return res.send('console.log("third party script")');
   });
   return app;
@@ -106,8 +113,8 @@ function thirdPartyApp(app = express()) {
 function baseTestApp(fpApp, tpApp, app = express(), fpHostname = firstPartyHostname, tpHostname = thirdPartyHostname) {
   let firstParty = firstPartyApp(fpApp),
     thirdParty = thirdPartyApp(tpApp);
-  app.use(vhost(fpHostname, firstParty));
-  app.use(vhost(tpHostname, thirdParty));
+  app.all('/', vhost(fpHostname, firstParty));
+  app.all('/tracker.js', vhost(tpHostname, thirdParty));
   Object.assign(app, {firstParty, thirdParty});
   return app;
 }
diff --git a/src/js/webrequest.js b/src/js/webrequest.js
index 3fd7931..87323f0 100644
--- a/src/js/webrequest.js
+++ b/src/js/webrequest.js
@@ -28,19 +28,19 @@ class WebRequest {
     onBeforeRequest.addListener(
       this.onBeforeRequest.bind(this),
       {urls: ["<all_urls>"]},
-      ["blocking"]
+      ["blocking"],
     );
 
     onBeforeSendHeaders.addListener(
       this.onBeforeSendHeaders.bind(this),
       {urls: ["<all_urls>"]},
-      ["blocking", "requestHeaders"]
+      ["blocking", "requestHeaders", "extraHeaders"],
     );
 
     onHeadersReceived.addListener(
       this.onHeadersReceived.bind(this),
       {urls: ["<all_urls>"]},
-      ["blocking", "responseHeaders"]
+      ["blocking", "responseHeaders", "extraHeaders"],
     );
   }