How to properly write tests for kernel functions

Hi all, I'm trying to understand is there any uniform way to write tests? For example, lib/ folder has a bunch of tests, but all of them use various technics: - pr_warn/pr_err (i.e. printk) or WARN for assertions - just tens of functions that check something, or unified macros - no naming convention for test cases So, I'm wondering, whether there is an example or guidelines that is worth to follow. Thanks!