How does Ristretto guarantee or verify its correctness?

According to the Ristretto README:

Ristretto is a fast, concurrent cache library built with a focus on performance and correctness.

I have been looking into the project but I could not find any formal specification. So, I’m wondering how does Ristretto checks or verifies the correctness of its algorithms, and workflows.

Thank you,

It’s eventual consistency model . and There is no guarantee that a set would be applied

thank you for your feedback