fix: evaluateAsync behavior

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

@@ -280,5 +280,6 @@ <h2>Do better web tester page</h2>
 }
 </script>
 
+<script src="./promise_polyfill.js"></script>
 </body>
 </html>

lighthouse-cli/test/fixtures/dobetterweb/promise_polyfill.js

@@ -0,0 +1,257 @@
+/*
+ * @license
+ * From taylorhakes/promise-polyfill
+
+ * Copyright (c) 2014 Taylor Hakes
+ * Copyright (c) 2014 Forbes Lindesay
+
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+*/
+'use strict';
+
+(function() {
+  /* eslint-disable */
+  // Store setTimeout reference so promise-polyfill will be unaffected by
+  // other code modifying setTimeout (like sinon.useFakeTimers())
+  var setTimeoutFunc = setTimeout;
+
+  function noop() {}
+
+  // Polyfill for Function.prototype.bind
+  function bind(fn, thisArg) {
+    return function () {
+      fn.apply(thisArg, arguments);
+    };
+  }
+
+  function Promise(fn) {
+    if (typeof this !== 'object') throw new TypeError('Promises must be constructed via new');
+    if (typeof fn !== 'function') throw new TypeError('not a function');
+    this._state = 0;
+    this._handled = false;
+    this._value = undefined;
+    this._deferreds = [];
+
+    doResolve(fn, this);
+  }
+
+  function handle(self, deferred) {
+    while (self._state === 3) {
+      self = self._value;
+    }
+    if (self._state === 0) {
+      self._deferreds.push(deferred);
+      return;
+    }
+    self._handled = true;
+    Promise._immediateFn(function () {
+      var cb = self._state === 1 ? deferred.onFulfilled : deferred.onRejected;
+      if (cb === null) {
+        (self._state === 1 ? resolve : reject)(deferred.promise, self._value);
+        return;
+      }
+      var ret;
+      try {
+        ret = cb(self._value);
+      } catch (e) {
+        reject(deferred.promise, e);
+        return;
+      }
+      resolve(deferred.promise, ret);
+    });
+  }
+
+  function resolve(self, newValue) {
+    try {
+      // Promise Resolution Procedure: https://github.com/promises-aplus/promises-spec#the-promise-resolution-procedure
+      if (newValue === self) throw new TypeError('A promise cannot be resolved with itself.');
+      if (newValue && (typeof newValue === 'object' || typeof newValue === 'function')) {
+        var then = newValue.then;
+        if (newValue instanceof Promise) {
+          self._state = 3;
+          self._value = newValue;
+          finale(self);
+          return;
+        } else if (typeof then === 'function') {
+          doResolve(bind(then, newValue), self);
+          return;
+        }
+      }
+      self._state = 1;
+      self._value = newValue;
+      finale(self);
+    } catch (e) {
+      reject(self, e);
+    }
+  }
+
+  function reject(self, newValue) {
+    self._state = 2;
+    self._value = newValue;
+    finale(self);
+  }
+
+  function finale(self) {
+    if (self._state === 2 && self._deferreds.length === 0) {
+      Promise._immediateFn(function() {
+        if (!self._handled) {
+          Promise._unhandledRejectionFn(self._value);
+        }
+      });
+    }
+
+    for (var i = 0, len = self._deferreds.length; i < len; i++) {
+      handle(self, self._deferreds[i]);
+    }
+    self._deferreds = null;
+  }
+
+  function Handler(onFulfilled, onRejected, promise) {
+    this.onFulfilled = typeof onFulfilled === 'function' ? onFulfilled : null;
+    this.onRejected = typeof onRejected === 'function' ? onRejected : null;
+    this.promise = promise;
+  }
+
+  /**
+   * Take a potentially misbehaving resolver function and make sure
+   * onFulfilled and onRejected are only called once.
+   *
+   * Makes no guarantees about asynchrony.
+   */
+  function doResolve(fn, self) {
+    var done = false;
+    try {
+      fn(function (value) {
+        if (done) return;
+        done = true;
+        resolve(self, value);
+      }, function (reason) {
+        if (done) return;
+        done = true;
+        reject(self, reason);
+      });
+    } catch (ex) {
+      if (done) return;
+      done = true;
+      reject(self, ex);
+    }
+  }
+
+  Promise.prototype['catch'] = function (onRejected) {
+    return this.then(null, onRejected);
+  };
+
+  Promise.prototype.then = function (onFulfilled, onRejected) {
+    var prom = new (this.constructor)(noop);
+
+    handle(this, new Handler(onFulfilled, onRejected, prom));
+    return prom;
+  };
+
+  Promise.all = function (arr) {
+    var args = Array.prototype.slice.call(arr);
+
+    return new Promise(function (resolve, reject) {
+      if (args.length === 0) return resolve([]);
+      var remaining = args.length;
+
+      function res(i, val) {
+        try {
+          if (val && (typeof val === 'object' || typeof val === 'function')) {
+            var then = val.then;
+            if (typeof then === 'function') {
+              then.call(val, function (val) {
+                res(i, val);
+              }, reject);
+              return;
+            }
+          }
+          args[i] = val;
+          if (--remaining === 0) {
+            resolve(args);
+          }
+        } catch (ex) {
+          reject(ex);
+        }
+      }
+
+      for (var i = 0; i < args.length; i++) {
+        res(i, args[i]);
+      }
+    });
+  };
+
+  Promise.resolve = function (value) {
+    if (value && typeof value === 'object' && value.constructor === Promise) {
+      return value;
+    }
+
+    return new Promise(function (resolve) {
+      resolve(value);
+    });
+  };
+
+  Promise.reject = function (value) {
+    return new Promise(function (resolve, reject) {
+      reject(value);
+    });
+  };
+
+  Promise.race = function (values) {
+    return new Promise(function (resolve, reject) {
+      for (var i = 0, len = values.length; i < len; i++) {
+        values[i].then(resolve, reject);
+      }
+    });
+  };
+
+  // Use polyfill for setImmediate for performance gains
+  Promise._immediateFn = (typeof setImmediate === 'function' && function (fn) { setImmediate(fn); }) ||
+    function (fn) {
+      setTimeoutFunc(fn, 0);
+    };
+
+  Promise._unhandledRejectionFn = function _unhandledRejectionFn(err) {
+    if (typeof console !== 'undefined' && console) {
+      console.warn('Possible Unhandled Promise Rejection:', err); // eslint-disable-line no-console
+    }
+  };
+
+  /**
+   * Set the immediate function to execute callbacks
+   * @param fn {function} Function to execute
+   * @deprecated
+   */
+  Promise._setImmediateFn = function _setImmediateFn(fn) {
+    Promise._immediateFn = fn;
+  };
+
+  /**
+   * Change the function to execute on unhandled rejection
+   * @param {function} fn Function to execute on unhandled rejection
+   * @deprecated
+   */
+  Promise._setUnhandledRejectionFn = function _setUnhandledRejectionFn(fn) {
+    Promise._unhandledRejectionFn = fn;
+  };
+
+  window.Promise = Promise;
+
+  /* eslint-enable */
+})();

lighthouse-core/audits/dobetterweb/link-blocking-first-paint.js

@@ -49,7 +49,8 @@ class LinkBlockingFirstPaintAudit extends Audit {
     if (typeof artifact === 'undefined' || artifact.value === -1) {
       return {
         rawValue: -1,
-        debugString: 'TagsBlockingFirstPaint gatherer did not run'
+        debugString: (artifact && artifact.debugString) ||
+            'TagsBlockingFirstPaint gatherer did not run'
       };
     }
 

lighthouse-core/gather/driver.js

@@ -143,17 +143,33 @@ class Driver {
         (_ => reject(new Error('The asynchronous expression exceeded the allotted time of 60s'))),
         60000
       );
+
       this.sendCommand('Runtime.evaluate', {
-        expression: asyncExpression,
+        expression: `(function wrapInNativePromise() {
+          const __nativePromise = window.__nativePromise || Promise;
+          return new __nativePromise(function(resolve) {
+            const wrapError = ${wrapRuntimeEvalErrorInBrowser.toString()};
+            try {
+              __nativePromise.resolve(${asyncExpression}).then(resolve, wrapError);
+            } catch (e) {
+              wrapError(e);
+            }
+          });
+        }())`,
         includeCommandLineAPI: true,
         awaitPromise: true,
         returnByValue: true
       }).then(result => {
         clearTimeout(asyncTimeout);
+        const value = result.result.value;
+
         if (result.exceptionDetails) {
-          reject(result.exceptionDetails.exception.value);
+          // An error occurred before we could even enter our try block, should be *very* rare
+          reject(new Error('an unknown driver error occurred'));
+        } if (value && value.__failedInBrowser) {
+          reject(Object.assign(new Error(), value));
         } else {
-          resolve(result.result.value);
+          resolve(value);
         }
       }).catch(err => {
         clearTimeout(asyncTimeout);
@@ -713,4 +729,24 @@ function captureJSCallUsage(funcRef, set) {
   };
 }
 
+/**
+ * The `exceptionDetails` provided by the debugger protocol does not contain the useful
+ * information such as name, message, and stack trace of the error when it's wrapped in a
+ * promise. Instead, map to a successful object that contains this information.
+ * @param {string|Error} err The error to convert
+ * istanbul ignore next
+ */
+function wrapRuntimeEvalErrorInBrowser(err) {
+  /* global resolve */
+  err = err || new Error();
+  const fallbackMessage = typeof err === 'string' ? err : 'unknown error';
+
+  resolve({
+    __failedInBrowser: true,
+    name: err.name || 'Error',
+    message: err.message || fallbackMessage,
+    stack: err.stack || (new Error()).stack,
+  });
+}
+
 module.exports = Driver;

lighthouse-core/gather/gather-runner.js

@@ -30,8 +30,10 @@ const path = require('path');
  *   C. GatherRunner.setupDriver()
  *     i. assertNoSameOriginServiceWorkerClients
  *     ii. beginEmulation
- *     iii. cleanAndDisableBrowserCaches
- *     iiii. clearDataForOrigin
+ *     iii. enableRuntimeEvents
+ *     iv. evaluateScriptOnLoad rescue native Promise from potential polyfill
+ *     v. cleanAndDisableBrowserCaches
+ *     vi. clearDataForOrigin
  *
  * 2. For each pass in the config:
  *   A. GatherRunner.beforePass()
@@ -90,6 +92,7 @@ class GatherRunner {
     return driver.assertNoSameOriginServiceWorkerClients(options.url)
       .then(_ => driver.beginEmulation(options.flags))
       .then(_ => driver.enableRuntimeEvents())
+      .then(_ => driver.evaluateScriptOnLoad('window.__nativePromise = Promise;'))
       .then(_ => driver.cleanAndDisableBrowserCaches())
       .then(_ => driver.clearDataForOrigin(options.url));
   }

lighthouse-core/gather/gatherers/accessibility.js

@@ -43,9 +43,13 @@ class Accessibility extends Gatherer {
 
   afterPass(options) {
     const driver = options.driver;
+    const expression = `(function () {
+      ${axe};
+      return (${runA11yChecks.toString()}());
+    })()`;
 
     return driver
-        .evaluateAsync(`${axe};(${runA11yChecks.toString()}())`)
+        .evaluateAsync(expression)
         .then(returnedValue => {
           if (!returnedValue) {
             this.artifact = Accessibility._errorAccessibility('Unable to parse axe results');

lighthouse-core/gather/gatherers/dobetterweb/tags-blocking-first-paint.js

@@ -53,7 +53,8 @@ function collectTagsThatBlockFirstPaint() {
         });
       resolve(tagList);
     } catch (e) {
-      reject(`Unable to gather Scripts/Stylesheets/HTML Imports on the page: ${e.message}`);
+      const friendly = 'Unable to gather Scripts/Stylesheets/HTML Imports on the page';
+      reject(new Error(`${friendly}: ${e.message}`));
     }
   });
 }
@@ -117,10 +118,10 @@ class TagsBlockingFirstPaint extends Gatherer {
       .then(artifact => {
         this.artifact = artifact;
       })
-      .catch(debugString => {
+      .catch(err => {
         this.artifact = {
           value: -1,
-          debugString
+          debugString: err.message
         };
       });
   }