Migrate evaluateAsync to Runtime.evaluate(awaitPromise)

lighthouse-core/gather/drivers/driver.js

@@ -144,50 +144,29 @@ class Driver {
     });
   }
 
+  /**
+   * Evaluate an expression in the context of the current page. Expression must
+   * evaluate to a Promise. Returns a promise that resolves on asyncExpression's
+   * resolved value.
+   * @param {string} asyncExpression
+   * @return {!Promise<*>}
+   */
   evaluateAsync(asyncExpression) {
     return new Promise((resolve, reject) => {
-      let asyncTimeout;
-
-      // Inject the call to capture inspection.
-      const expression = `(function() {
-        const __inspect = inspect;
-        const __returnResults = function(results) {
-          __inspect(JSON.stringify(results));
-        };
-        ${asyncExpression}
-      })()`;
-
-      const inspectHandler = value => {
-        if (asyncTimeout !== undefined) {
-          clearTimeout(asyncTimeout);
-        }
-
-        // If the returned object doesn't meet the expected pattern, bail with an undefined.
-        if (value === undefined ||
-            value.object === undefined ||
-            value.object.value === undefined) {
-          return resolve();
-        }
-
-        return resolve(JSON.parse(value.object.value));
-      };
-
-      // COMPAT: Chrome 52 is when Runtime.inspectRequested became available
-      //   https://codereview.chromium.org/1866213002
-      // Previously, a similar-looking Inspector.inspect event was available, but unfortunately
-      // it will not fire in this scenario.
-      this.once('Runtime.inspectRequested', inspectHandler);
-
-      this.sendCommand('Runtime.evaluate', {
-        expression,
-        includeCommandLineAPI: true
-      }).catch(reject);
-
       // If this gets to 60s and it hasn't been resolved, reject the Promise.
-      asyncTimeout = setTimeout(
+      const asyncTimeout = setTimeout(
         (_ => reject(new Error('The asynchronous expression exceeded the allotted time of 60s'))),
         60000
       );
+      this.sendCommand('Runtime.evaluate', {
+        expression: asyncExpression,
+        includeCommandLineAPI: true,
+        awaitPromise: true,
+        returnByValue: true
+      }).then(result => {
+        clearTimeout(asyncTimeout);
+        resolve(result.result.value);
+      }).catch(reject);
     });
   }
 

lighthouse-core/gather/gatherers/accessibility.js

@@ -16,7 +16,7 @@
  */
 'use strict';
 
-/* global document, __returnResults */
+/* global document */
 
 const Gatherer = require('./gatherer');
 const fs = require('fs');
@@ -27,9 +27,8 @@ const axe = fs.readFileSync(
 // This is run in the page, not Lighthouse itself.
 /* istanbul ignore next */
 function runA11yChecks() {
-  axe.a11yCheck(document, function(results) {
-    // __returnResults is magically inserted by driver.evaluateAsync
-    __returnResults(results);
+  return new Promise((resolve, reject) => {
+    axe.a11yCheck(document, resolve);
   });
 }
 

lighthouse-core/gather/gatherers/cache-contents.js

@@ -16,15 +16,15 @@
  */
 'use strict';
 
-/* global __returnResults, caches */
+/* global caches */
 
 const Gatherer = require('./gatherer');
 
 // This is run in the page, not Lighthouse itself.
 /* istanbul ignore next */
 function getCacheContents() {
   // Get every cache by name.
-  caches.keys()
+  return caches.keys()
 
       // Open each one.
       .then(cacheNames => Promise.all(cacheNames.map(cacheName => caches.open(cacheName))))
@@ -39,11 +39,8 @@ function getCacheContents() {
                 requests.push(...reqs.map(r => r.url));
               });
         })).then(_ => {
-          // __returnResults is magically inserted by driver.evaluateAsync
-          __returnResults(requests);
+          return requests;
         });
-      }).catch(_ => {
-        __returnResults(undefined);
       });
 }
 

lighthouse-core/gather/gatherers/content-width.js

@@ -18,13 +18,13 @@
 
 const Gatherer = require('./gatherer');
 
-/* global window, __returnResults */
+/* global window */
 
 /* istanbul ignore next */
 function getContentWidth() {
   // window.innerWidth to get the scrollable size of the window (irrespective of zoom)
   // window.outerWidth to get the size of the visible area
-  __returnResults({
+  return Promise.resolve({
     scrollWidth: window.innerWidth,
     viewportWidth: window.outerWidth
   });

lighthouse-core/gather/gatherers/geolocation-on-start.js

@@ -26,7 +26,7 @@ const Gatherer = require('./gatherer');
  * @author Paul Lewis
  */
 
-/* global navigator, window, __returnResults */
+/* global navigator, window */
 
 /* istanbul ignore next */
 function overrideGeo() {
@@ -39,7 +39,7 @@ function overrideGeo() {
 }
 
 function collectGeoState() {
-  __returnResults(window.__didNotCallGeo);
+  return Promise.resolve(window.__didNotCallGeo);
 }
 
 class GeolocationOnStart extends Gatherer {

lighthouse-core/gather/gatherers/html-without-javascript.js

@@ -20,14 +20,13 @@
 
 const Gatherer = require('./gatherer');
 
-/* global document, __returnResults */
+/* global document */
 
 /* istanbul ignore next */
 function getBodyText() {
   // note: we use innerText, not textContent, because textContent includes the content of <script> elements!
   const body = document.querySelector('body');
-  // __returnResults is magically inserted by driver.evaluateAsync
-  __returnResults(body ? body.innerText : '');
+  return Promise.resolve(body ? body.innerText : '');
 }
 
 class HTMLWithoutJavaScript extends Gatherer {