// errors1.rs // // This function refuses to generate text to be printed on a nametag if you pass // it an empty string. It'd be nicer if it explained what the problem was, // instead of just sometimes returning `None`. Thankfully, Rust has a similar // construct to `Option` that can be used to express error conditions. Let's use // it! // // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a // hint. pub fn generate_nametag_text(name: String) -> Result { if name.is_empty() { Err(format!("`name` was empty; it must be nonempty.")) } else { Ok(format!("Hi! My name is {}", name)) } } #[cfg(test)] mod tests { use super::*; #[test] fn generates_nametag_text_for_a_nonempty_name() { assert_eq!( generate_nametag_text("Beyoncé".into()), Ok("Hi! My name is Beyoncé".into()) ); } #[test] fn explains_why_generating_nametag_text_fails() { assert_eq!( generate_nametag_text("".into()), // Don't change this line Err("`name` was empty; it must be nonempty.".into()) ); } }