Reuse cache between launches in headless mode

Steps to reproduce

Tell us about your environment:

• Puppeteer version: 1.3.0
• Platform / OS version: Linux / CentOS 7.4.1708
• Node.js version: 8.11.1

What steps will reproduce the problem?

1. Run the script (userDataDir is expected to be empty)

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch({
    userDataDir: '/tmp/user-data-dir',
    headless: true,
    args: ['--no-sandbox'],
  });

  const page = await browser.newPage();
  const response = await page.goto('https://example.com/');
  console.log(response.fromCache());

  await browser.close();
})();

Console:

false

1. Run the script for the second time

What is the expected result?

true

What happens instead?

false

Puppeteer works as expected in headfull mode, though.

[blackdeman]

The initial script works for me on v1.18.1. But it doesn’t work when request interception is on.

const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch({
    userDataDir: '/tmp/user-data-dir',
    headless: true,
    args: ['--no-sandbox'],
  });

  const page = await browser.newPage();

  // enable request interception
  await page.setRequestInterception(true);
  page.on('request', request => {
    request.continue();
  });

  const response = await page.goto('https://example.com/');
  console.log(response.fromCache());

  await browser.close();
})();

I have found out that page.setRequestInterception(true) method disables cache. Indeed; there is a test in puppeteer (page.spec.js) which says that page cache ‘should stay disabled when toggling request interception on/off’. @aslushnikov, can you please explain the idea behind that test? Is it safe to manually enable cache when request interception is on?

await page._client.send('Network.setCacheDisabled', {
  cacheDisabled: false
});

[JohnBruce]

fwiw, still seeing this on puppeteer@1.7.0

Its not the end of the world, but there are use cases where reusing/sharing a cache across multiple browser instances makes sense, so it would be cool if this could be addressed.