* Visit a page with discussion tools and parsoid enabled, for example: https://en.wikivoyage.org/wiki/Talk:Western_food_in_Asia?useparsoid=1
* Scroll to the very bottom and click on "Mobile view"
* Note that the Discussion Tools "information bar" is missing under each heading. For example, under the first heading in desktop view reads "Latest comment: 4 years ago | 8 comments | 6 people in discussion", but in mobile view it just says "Latest comment: 4 years ago".
* Open the JavaScript console and note the uncaught "Type Error: startMarker is null" on the console.
* Click on any of the "reply" buttons: nothing happens.
* Click the "add topic" button: nothing happens.
With the patch the mobile and desktop views should display the same information under the heading and there should be no JavaScript error on the console. The Reply and Add Topic buttons should work. T376048#10268521 has a few other items you can test.