Headless test runner

[kateinoigakukun]

Motivation

carton test --environment defaultBrowser only works on macOS or X Window systems, so tests using browser APIs cannot be run on CI easily. Add a headless test runner based on WebDriver.

Changed

• Add WebDriverClient module, which is a thin client of W3C WebDriver: https://w3c.github.io/webdriver/
• Add --headless option to carton test

[MaxDesiatov]

Is this new option compatible with other --environment values? If not, maybe it should be implemented as --environment webdriver?

[kateinoigakukun]

@MaxDesiatov I made it as a new flag instead of a --environment variant because I thought --environment is designed to accept specific browser names in the future like --environment firefox and then --headless should be able to be used with defaultBrowser and other browser values.

[MaxDesiatov]

That makes sense, thanks!

[MaxDesiatov]

Great work, thanks! 👏