[BUG] route.fulfill failed with TimeoutError if the response headers contains newline

[char101]

Context:

• Playwright Version: 1.0.2
• Operating System: Windows
• Node version: 14.2.0
• Browser: chromium

Code Snippet

const { chromium } = require('playwright');

(async () => {
  const browser = await chromium.launch();
  const context = await browser.newContext();
  await context.route('**/*', async route => {
    route.fulfill({
      status: 200,
      headers: {
        x: 'a\nb',
      },
      body: '<h1>Title</h1>',
    });
  });
  const page = await context.newPage();
  await page.goto('http://localhost/');
  console.log(await page.content());
  await browser.close();
})();

Describe the bug

route.fulfill hang if fed with response containing newline in its value but on the other hand response.headers() joins multiple headers (like multiple set-cookie headers) into a single line separated with newline.

set-cookie: a
set-cookie: b

becomes

{'set-cookie': 'a\nb'}

when fetch via response.headers().
I think there should be a standard on how to handle header field with multiple values. Having it returns and receive Array is better in my opinion.

[JoelEinbinder]

I think there should be a standard on how to handle header field with multiple values. Having it returns and receive Array is better in my opinion.

Agreed. It is a little bit more involved because we need to maintain backwards compatibility with the objects. Filed as #3184 .