From 1c2adf61e971577a6bc96621fcb78ee88a9a9ff8 Mon Sep 17 00:00:00 2001
From: Joel Einbinder <joel.einbinder@gmail.com>
Date: Wed, 30 May 2018 18:08:27 -0700
Subject: [PATCH] fix(workers): workaround worker execution context flakiness
 (#2596)

Some of the worker tests were failing on the bots. After investigating, I found one race in the test, and one race upstream in Chromium which I filed upstream as https://crbug.com/846099. But I added a small hack here as a temporary workaround.

References #2632
---
 lib/Worker.js     | 8 +++++++-
 test/page.spec.js | 5 +++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/Worker.js b/lib/Worker.js
index 42a47f89..f3bdf1b0 100644
--- a/lib/Worker.js
+++ b/lib/Worker.js
@@ -28,7 +28,13 @@ class Worker extends EventEmitter {
     this._client = client;
     this._url = url;
     this._executionContextPromise = new Promise(x => this._executionContextCallback = x);
-    this._client.on('Runtime.executionContextCreated', event => {
+    this._client.once('Runtime.executionContextCreated', async event => {
+      // Get a reference to the main object on the worker as a hack around https://crbug.com/846099.
+      await this._client.send('Runtime.evaluate', {
+        expression: 'this',
+        returnByValue: false,
+        contextId: event.executionContextId
+      }).catch(debugError);
       const jsHandleFactory = remoteObject => new JSHandle(executionContext, client, remoteObject);
       const executionContext = new ExecutionContext(client, event.context, jsHandleFactory, null);
       this._executionContextCallback(executionContext);
diff --git a/test/page.spec.js b/test/page.spec.js
index 6982c829..4ab13b7d 100644
--- a/test/page.spec.js
+++ b/test/page.spec.js
@@ -1627,8 +1627,9 @@ module.exports.addTests = function({testRunner, expect, puppeteer, DeviceDescrip
   });
   describe('Workers', function() {
     it('Page.workers', async function({page, server}) {
-      await page.goto(server.PREFIX + '/worker/worker.html');
-      await page.waitForFunction(() => !!worker);
+      await Promise.all([
+        new Promise(x => page.once('workercreated', x)),
+        page.goto(server.PREFIX + '/worker/worker.html')]);
       const worker = page.workers()[0];
       expect(worker.url()).toContain('worker.js');
       const executionContext = await worker.executionContext();