Create an Appliance test harness

[slifty]

Task

Description

In order to really test an appliance we need to be able to pipe a Payload input stream and check the Payload output stream, this is going to be common for all appliances.

There could be value in some kind of common test utilities package that appliances can add as a dev dependency. I think eslint does something similar for their ecosystem.

Relevant Resources / Research

None

Related Issues

None

[slifty]

This test harness should also do thinks like:

1. ensure that appliances have implemented all required method.
2. ensure that super is properly called for various methods.

[slifty]

Related to this need -- a "record" mode for a countertop, which will write payloads (and maybe even raw video) of various types to a file. This can then be used to create tests from the relevant payload sections.