I read some of the docs, checked the examples, and read trough ringabout's dev.to tutorial of Testament Tutorial. But i cannot get it to run any test, and i've tried several. I don't get it.
Here is an example from ringabout's tutorial that is just not running for me, or i have no idea what is going on when giving it the full path: My Problem
Testament requires the tests to be stored in a proper directories' hierarchy. For example, Nim tests: https://github.com/nim-lang/Nim/tree/devel/tests
Example of working structure. The tests are in tests/directory/test.nim and tests/directory2/anothertest.nim. If you have that structure, then in the main project's directory, where project.nimble file is, execute the command testament all.
Another option is to use the package std/unittest (or unittest2, the external package). It is similar to unit tests libraries from other languages like C++ or Java.
As @thindil suggested, you may want to use std/unittest. It generally works great for small projects where you may not need any of Testament's cool features like multiple targets or report generation.
Here is an example of a test file. If you want to have several of them, you can write a simple convenience script like this one here to run them in a particular order, and then conveniently deploy them with a GitHub Action workflow like this one here.