https://www.w3.org/TR/webdriver/#dfn-get-computed-role

Current spec:

12.4.9 Get Computed Role
HTTP Method 	URI Template
GET 	/session/{session id}/element/{element id}/computedrole

The remote end steps are:

    If the current browsing context is no longer open, return error with error code no such window.

    Handle any user prompts and return its value if it is an error.

    Let element be the result of trying to get a known connected element with url variable element id.

    Let role be the result of computing the WAI-ARIA role of element.

    Return success with data role. 



Tests:

imported/w3c/webdriver/tests/get_computed_role/