hello_cli/
lib.rs

1pub fn build_message(opt_name: Option<&str>) -> String {
2    let name = opt_name.unwrap_or("World");
3    return format!("Hello {}!", name);
4}
5
6#[cfg(test)]
7mod tests {
8    use super::*;
9
10    #[test]
11    fn build_message_none() {
12        let message = build_message(None);
13        assert_eq!(message, "Hello World!");
14    }
15
16    #[test]
17    fn build_message_some() {
18        let message = build_message(Some("MyName"));
19        assert_eq!(message, "Hello MyName!");
20    }
21}