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// 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!
fn main() {
// You can optionally experiment here.
}
pub fn generate_nametag_text(name: String) -> Option<String> {
if name.is_empty() {
// Empty names aren't allowed.
None
} else {
Some(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())
);
}
}
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