There is a manual wpt test for drag interaction, https://github.com/web-platform-tests/wpt/blob/07eb92b7cd5b99e80f949a91ff93a8cf57b85cd2/pointerevents/html/pointerevent_drag_interaction-manual.html. I could try to cover it to an automatic test by using webdriver.
Bug 1669673 Comment 3 Edit History
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There is a manual wpt test for drag interaction, https://github.com/web-platform-tests/wpt/blob/07eb92b7cd5b99e80f949a91ff93a8cf57b85cd2/pointerevents/html/pointerevent_drag_interaction-manual.html. I could try to convert it to an automatic test by using webdriver.