With crrev.com/c/6021359 landing for chrome-headless-shell, there is now a way to test web applications with various screen configurations without having the physical devices or resorting to other ways to emulate them on the operating system level. Although this works for the headless shell, there is currently no standard way for developers to test Window Management in major browsers.

Given that it might be difficult to set up a test environment for web apps relying on various screen configurations, I think it would be great if this specification defined how a test interface should look like and how it should integrate with the rest of the implementation.

WebDriver BiDi standard already has some window management capabilities:

• https://w3c.github.io/webdriver-bidi/#command-browser-setClientWindowState
• https://w3c.github.io/webdriver-bidi/#command-browser-getClientWindows

There are a few examples of external specifications extending WebDriver BiDi already:

• https://webbluetoothcg.github.io/web-bluetooth/#automated-testing
• https://www.w3.org/TR/permissions/#automation-webdriver-bidi