Design review: Design for Test

[krook]

Implement an automated build and test system including unit tests and coverage.

Generally, each feature critical to the design should include unit tests. Ideally, these tests could either be performed in an emulated environment or directly on the hardware using a test harness. Zephyr RTOS includes a test framework that supports this, otherwise, Unity is another common test framework that can be used.

It should be recommended to community developers that new features be introduced with test coverage of some specified minimum threshold, i.e. 70-80% test coverage on new features, in the same PR as the feature.