REST API test coverage (ancestors functionality)

[lsulak]

Background

This is a continuation of this ticket: #361 that covered 100% of REST API endpoints during that time.

But there will be new ones that needs covering, see dependencies below.

Depends on: #273
Depends on: #305

Note: there are 2 more endpoints: 346d406 liveness and readiness, but it's the same as the health one already covered. Consider calling these as well for the sake of completeness.

Feature

All REST API Endpoints are covered.