How to move tests into a separate file for binaries in Rust's Cargo?

Question

I created a new binary using Cargo:

cargo new my_binary --bin

A function in my_binary/src/main.rs can be used for a test:

Answer 1

You're right; function_from_main is inaccessible outside of main.rs.

You need to create an src/lib.rs and move the functions you want to test piecemeal. Then you'll be able to use extern crate my_binary; from your test module, and have your functions appear under the my_binary namespace.