What's the usual way to test a private function?

[na-sa-do]

Most of my recent programming has been Rust (not that I've liked the language overall... but that's why I'm here). In Rust, the idiomatic way to structure tests is to put them in the same file as the code being tested and remove them from non-test builds with what boils down to an #ifdef. This means tests can easily access non-exported names from the parent module.

In Janet, on the other hand, it seems like the idiom is to put tests in separate files, which means they can't access private functions. Unless I'm missing something?

[sogaiu]

Not sure if there is an idiom or a usual way.

There is some discussion about testing private things here.