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