[BUG]: recently added support for `"new"` headless mode fails with Playwright

[dgrebb]

Summary

As documented in the README, setting engineOptions.headless = "new" is passed to Playwright as expected, but fails.

backstopjs@6.3.2

Creating Browser
No Playwright browser specified, assuming Chromium.
      COMMAND | Command "test" ended with an error after [0.003s]
      COMMAND | browserType.launch: headless: expected boolean, got string

Details

Playwright supports "new" headless mode, set as a string, but only by defining ignoredDefaultArgs: ["--headless"].

This isn't well documented, but one can see Playwright's headless argument expects a boolean.

Deeply burred in a GitHub issue, there is a small example of how to make "new" headless mode work:

  projects: [
    {
      name: 'chromium',
      use: {
        launchOptions: {
          ignoreDefaultArgs: ['--headless'],
          args: ['--headless=new']
        }
      },
    },

(#1525) (dgrebb#73)

[dgrebb]

Found and fixing 👍

[dgrebb]

Closed with #1535