Context

Currently our Lua tests don't use any testing framework, moreover the tests could be better organized and be more systematic. Also there are many Lua functions that we have bindings but don't provide tests yet, we should improve this.

Possible solutions

The Lua tests should be refactored using unit style testing using a Lua testing framework, I suggest to use https://github.com/edubart/lester , because of its simplicity and minimalist.