Fault injection framework for Zephyr

[zephyrbot]

Reported by Paul Sokolovsky:

For many subsystems in Zephyr, there're multiple error-handling and recovery paths which are hard to test with normal unit tests, especially if these paths depends on external entity behavior. This is in particular true for networking. We already saw various cases of problems on these paths (see e.g. #73), and the common impression is that likely we have many problems.

To address this problem, we need some kind of fault injection framework. And probably, this matter should be handled from "top" (from Zephyr architects/PM level), because developers would try to avoid this matter for as long as possible, and when faced the need for it, would go for adhoc solutions, inconsistent in different parts of the tree, and leading to maintenance problems. Instead, we'd rather have consistent fault injection architecture and API for the entire tree.

Example of an adhoc approach to fault injection (from the discussion in the ticket above): https://github.com/pfalcon/zephyr/commits/net-pkt-fault-inject

(Imported from Jira ZEP-2118)

[carlescufi]

@ceolin if this is planned for a particular release please let us know