From 64d95837e9813541cf5b357de13865ce687ae98d Mon Sep 17 00:00:00 2001 From: Adam Brewer Date: Mon, 16 Oct 2023 07:37:12 -0400 Subject: Update Exercises Directory Names to Reflect Order --- exercises/13_error_handling/errors2.rs | 50 ++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 exercises/13_error_handling/errors2.rs (limited to 'exercises/13_error_handling/errors2.rs') diff --git a/exercises/13_error_handling/errors2.rs b/exercises/13_error_handling/errors2.rs new file mode 100644 index 0000000..631fe67 --- /dev/null +++ b/exercises/13_error_handling/errors2.rs @@ -0,0 +1,50 @@ +// errors2.rs +// +// Say we're writing a game where you can buy items with tokens. All items cost +// 5 tokens, and whenever you purchase items there is a processing fee of 1 +// token. A player of the game will type in how many items they want to buy, and +// the `total_cost` function will calculate the total cost of the items. Since +// the player typed in the quantity, though, we get it as a string-- and they +// might have typed anything, not just numbers! +// +// Right now, this function isn't handling the error case at all (and isn't +// handling the success case properly either). What we want to do is: if we call +// the `total_cost` function on a string that is not a number, that function +// will return a `ParseIntError`, and in that case, we want to immediately +// return that error from our function and not try to multiply and add. +// +// There are at least two ways to implement this that are both correct-- but one +// is a lot shorter! +// +// Execute `rustlings hint errors2` or use the `hint` watch subcommand for a +// hint. + +// I AM NOT DONE + +use std::num::ParseIntError; + +pub fn total_cost(item_quantity: &str) -> Result { + let processing_fee = 1; + let cost_per_item = 5; + let qty = item_quantity.parse::(); + + Ok(qty * cost_per_item + processing_fee) +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn item_quantity_is_a_valid_number() { + assert_eq!(total_cost("34"), Ok(171)); + } + + #[test] + fn item_quantity_is_an_invalid_number() { + assert_eq!( + total_cost("beep boop").unwrap_err().to_string(), + "invalid digit found in string" + ); + } +} -- cgit v1.2.3