Spending short lifetime for development and boring things.– $argon2id$v=19$m=512,t=256,p=1$J7IZNfNG3RC2FiSRzZfQzw$0seu3KTpAnSufFxXDbHccXnX81enF+A++beI9VvHVVA
I see. I suppose that exa is abandoned for two years or more and perhaps there’s no connection with maintainer. So then fork.
Testing interface is not about exactly interface as language’s feature. It’s about testing outer public interface (public API) of you things, looking at it as a black-box and doesn’t matter what happens inside. That's all it means.
Take a look at cargo-tree’s deps, there was something.