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rustlings-exercises-completed/exercises/iterators/iterators3.rs

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// iterators3.rs
// This is a bigger exercise than most of the others! You can do it!
// Here is your mission, should you choose to accept it:
// 1. Complete the divide function to get the first four tests to pass.
// 2. Get the remaining tests to pass by completing the result_with_list and
// list_of_results functions.
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// Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a hint.
#[derive(Debug, PartialEq, Eq)]
pub enum DivisionError {
NotDivisible(NotDivisibleError),
DivideByZero,
}
#[derive(Debug, PartialEq, Eq)]
pub struct NotDivisibleError {
dividend: i32,
divisor: i32,
}
// Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
// Otherwise, return a suitable error.
pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
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match b {
0 => Err(DivisionError::DivideByZero),
_ => match a % b {
0 => Ok(a / b),
_ => Err(DivisionError::NotDivisible(NotDivisibleError {
dividend: a,
divisor: b,
})),
},
}
}
// Complete the function and return a value of the correct type so the test passes.
// Desired output: Ok([1, 11, 1426, 3])
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fn result_with_list() -> Result<Vec<i32>, DivisionError> {
let numbers = vec![27, 297, 38502, 81];
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match numbers
.into_iter()
.map(|n| match divide(n, 27) {
Ok(r) => Ok(r),
Err(e) => return Err(e),
})
.collect()
{
Ok(v) => Ok(v),
Err(e) => Err(e),
}
}
// Complete the function and return a value of the correct type so the test passes.
// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
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fn list_of_results() -> Vec<Result<i32, DivisionError>> {
let numbers = vec![27, 297, 38502, 81];
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numbers
.into_iter()
.map(|n| match divide(n, 27) {
Ok(r) => Ok(r),
Err(e) => return Err(e),
})
.collect()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_success() {
assert_eq!(divide(81, 9), Ok(9));
}
#[test]
fn test_not_divisible() {
assert_eq!(
divide(81, 6),
Err(DivisionError::NotDivisible(NotDivisibleError {
dividend: 81,
divisor: 6
}))
);
}
#[test]
fn test_divide_by_0() {
assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
}
#[test]
fn test_divide_0_by_something() {
assert_eq!(divide(0, 81), Ok(0));
}
#[test]
fn test_result_with_list() {
assert_eq!(format!("{:?}", result_with_list()), "Ok([1, 11, 1426, 3])");
}
#[test]
fn test_list_of_results() {
assert_eq!(
format!("{:?}", list_of_results()),
"[Ok(1), Ok(11), Ok(1426), Ok(3)]"
);
}
}