diff options
| author | olivia <olivia@fastmail.com> | 2018-11-09 20:31:14 +0100 |
|---|---|---|
| committer | olivia <olivia@fastmail.com> | 2018-11-09 20:31:14 +0100 |
| commit | f7846af7ac388652a6f80a2bbce926ba8f053062 (patch) | |
| tree | 954ee36257047ac612654c5f35e18ed27deda97f /exercises/error_handling/errors1.rs | |
| parent | 850a13e9133fedb2fce27884902e0aab94da9692 (diff) | |
right let's try this one again
Diffstat (limited to 'exercises/error_handling/errors1.rs')
| -rwxr-xr-x | exercises/error_handling/errors1.rs | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/exercises/error_handling/errors1.rs b/exercises/error_handling/errors1.rs new file mode 100755 index 0000000..14ed574 --- /dev/null +++ b/exercises/error_handling/errors1.rs @@ -0,0 +1,73 @@ +// 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`. The 2nd test currently +// does not compile or pass, but it illustrates the behavior we would like +// this function to have. +// Scroll down for hints!!! + +pub fn generate_nametag_text(name: String) -> Option<String> { + if name.len() > 0 { + Some(format!("Hi! My name is {}", name)) + } else { + // Empty names aren't allowed. + None + } +} + +#[cfg(test)] +mod tests { + use super::*; + + // This test passes initially if you comment out the 2nd test. + // You'll need to update what this test expects when you change + // the function under test! + #[test] + fn generates_nametag_text_for_a_nonempty_name() { + assert_eq!( + generate_nametag_text("Beyoncé".into()), + Some("Hi! My name is Beyoncé".into()) + ); + } + + #[test] + fn explains_why_generating_nametag_text_fails() { + assert_eq!( + generate_nametag_text("".into()), + Err("`name` was empty; it must be nonempty.".into()) + ); + } +} + + + + + + + + + + + + + + + + + + + + +// `Err` is one of the variants of `Result`, so what the 2nd test is saying +// is that `generate_nametag_text` should return a `Result` instead of an +// `Option`. + +// To make this change, you'll need to: +// - update the return type in the function signature to be a Result that +// could be the variants `Ok(String)` and `Err(String)` +// - change the body of the function to return `Ok(stuff)` where it currently +// returns `Some(stuff)` +// - change the body of the function to return `Err(error message)` where it +// currently returns `None` +// - change the first test to expect `Ok(stuff)` where it currently expects +// `Some(stuff)`. |
