Fix evaluateAsync in the face of aggressive Promise polyfills (Google…

…Chrome#1178)

* Fix `driver.evaluateAsync` behavior when [zone.js](https://github.com/angular/zone.js) has mucked with Promise.

* Add zone.js to the smoke tests so regression won't happen again.

* Remove old testing promise-polyfill

lighthouse-cli/test/fixtures/dobetterweb/dbw_tester.html

@@ -295,6 +295,6 @@ <h2>Do better web tester page</h2>
 }
 </script>
 
-<script src="/promise_polyfill.js"></script>
+<script src="/zone.js"></script>
 </body>
 </html>

lighthouse-cli/test/fixtures/static-server.js

@@ -27,11 +27,11 @@ function requestHandler(request, response) {
   const queryString = requestUrl.search;
   let absoluteFilePath = path.join(__dirname, filePath);
 
-  if (filePath === '/promise_polyfill.js') {
+  if (filePath === '/zone.js') {
     // evaluateAsync previously had a bug that LH would fail if a page polyfilled Promise.
-    // We bring in a third-party Promise polyfill to ensure we don't still fail.
-    const thirdPartyPath = '../../../lighthouse-core/third_party';
-    absoluteFilePath = path.join(__dirname, `${thirdPartyPath}/promise-polyfill/promise.js`);
+    // We bring in an aggressive Promise polyfill (zone) to ensure we don't still fail.
+    const zonePath = '../../../node_modules/zone.js';
+    absoluteFilePath = path.join(__dirname, `${zonePath}/dist/zone.js`);
   }
 
   fs.exists(absoluteFilePath, fsExistsCallback);

lighthouse-core/gather/driver.js

@@ -143,15 +143,19 @@ class Driver {
       );
 
       this.sendCommand('Runtime.evaluate', {
-        // We need to wrap the raw expression for several purposes
+        // We need to explicitly wrap the raw expression for several purposes:
         // 1. Ensure that the expression will be a native Promise and not a polyfill/non-Promise.
-        // 2. Ensure that errors captured in the Promise are converted into plain-old JS Objects
+        // 2. Ensure that errors in the expression are captured by the Promise.
+        // 3. Ensure that errors captured in the Promise are converted into plain-old JS Objects
         //    so that they can be serialized properly b/c JSON.stringify(new Error('foo')) === '{}'
         expression: `(function wrapInNativePromise() {
           const __nativePromise = window.__nativePromise || Promise;
-          return __nativePromise.resolve()
-            .then(_ => ${expression})
-            .catch(${wrapRuntimeEvalErrorInBrowser.toString()});
+          return new __nativePromise(function (resolve) {
+            return __nativePromise.resolve()
+              .then(_ => ${expression})
+              .catch(${wrapRuntimeEvalErrorInBrowser.toString()})
+              .then(resolve);
+          });
         }())`,
         includeCommandLineAPI: true,
         awaitPromise: true,

package.json

@@ -41,7 +41,8 @@
     "jsdom": "^9.0.0",
     "mkdirp": "^0.5.1",
     "mocha": "^2.3.3",
-    "walk": "^2.3.9"
+    "walk": "^2.3.9",
+    "zone.js": "^0.7.3"
   },
   "dependencies": {
     "axe-core": "2.1.7",
@@ -52,13 +53,13 @@
     "handlebars": "^4.0.5",
     "json-stringify-safe": "^5.0.1",
     "mkdirp": "^0.5.1",
+    "opn": "^4.0.2",
     "rimraf": "^2.2.8",
     "semver": ">=4.3.3",
     "speedline": "1.0.3",
     "whatwg-url": "^4.0.0",
     "ws": "^1.1.1",
-    "yargs": "3.30.0",
-    "opn": "^4.0.2"
+    "yargs": "3.30.0"
   },
   "repository": "googlechrome/lighthouse",
   "keywords": [

yarn.lock

@@ -2873,3 +2873,7 @@ yargs@~3.10.0:
     cliui "^2.1.0"
     decamelize "^1.0.0"
     window-size "0.1.0"
+
+zone.js@^0.7.3:
+  version "0.7.3"
+  resolved "https://registry.yarnpkg.com/zone.js/-/zone.js-0.7.3.tgz#d91432b6584f73c2c9e03ce4bb0870becc45d445"