Specifications with matching test APIs

As a followup to this thread
<https://lists.w3.org/Archives/Public/public-test-infra/2017AprJun/0013.html>
on
UserAgent-specific files in Web Platform Tests I would like to draw this
group's attention to the WebUSB Testing API
<https://wicg.github.io/webusb/test/>. This specification formally defines
an additional API that can be implemented by a UA to permit automated
testing of hard-to-test APIs such as WebUSB and Web Bluetooth. Some example
tests are included.

The specification is based on the behavior of the existing test API used in
Chromium's LayoutTests for WebUSB which I am currently in the process of
upstreaming to Web Platform Tests. The goal is to provide a way for
implementations of the WebUSB API to test the web-exposed semantics of
their implementation. It does not of course guarantee that their
implementation communicates with a physical USB device correctly but still
has value because there is a reasonably sized state machine and parameter
validation logic that be tested in this way. A separate test suite that
relies on physical hardware is something I would like to build however that
would not be compatible with integration into an implementer's existing
testing waterfalls and the like.

I am seeking consensus among this group that there is value to other
implementers in adding tests based on this sort of formally specified
testing interface to the Web Platform Tests repository.