#![allow(non_camel_case_types)] #![allow(dead_code)] #[derive(Clone, Debug)] enum foo { a(usize), b(String), } fn check_log(exp: String, v: T) { assert_eq!(exp, format!("{:?}", v)); } #[test] fn log_knows_the_names_of_variants_in_std() { let mut x = Some(foo::a(22)); let exp = "Some(a(22))".to_string(); let act = format!("{:?}", x); assert_eq!(act, exp); check_log(exp, x); x = None; let exp = "None".to_string(); let act = format!("{:?}", x); assert_eq!(act, exp); check_log(exp, x); }