Given a contract method that transfer funds:
Promise::new("b.testnet".to_string()).transfer(near_sdk::env::attached_deposit())
How should you write a unit test that checks that the funds were transferred?
Because this is call from one contract to another, you cannot use unit tests to verify expected behavior.
Check out simulation tests here https://crates.io/crates/near-sdk-sim
This works on Rust as well as AssemblyScript contracts because you're actually testing the compiled contract as a Wasm binary