Testing shall by done by means of automated testing and hand sampling.
Test-Tier 1: user point of view (pov) tests
The highest tier focusses mainly on usage scenario's from a user point of view.
Goal is to automate scenario's and verify them. We automate normal user programmed behaviour like login, send messages and test the correctness of security (TLS etc) via scenario's and verify if the scenario's "works" as expected.
Test-Tier 2: integration tests
This tier focusses on the FB's internals (aka integration tests) and mainly on the "glue logic". Tests on this tier are focussed on the outside of various composite FB's.
Test-Tier 3: unit tests
This test tier focusses on the methods/functions on the lowest level of the library.