// iterator3.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. Uncomment the last two tests and get them to pass by filling in
// values for `x` using `division_results`.
// Scroll down for a minor hint for part 2, and scroll down further for
// a major hint.
// Have fun :-)
#[ derive(Debug, PartialEq, Eq) ]
pub enum DivisionError {
NotDivisible ( NotDivisibleError ) ,
DivideByZero ,
}
#[ derive(Debug, PartialEq, Eq) ]
pub struct NotDivisibleError {
dividend : i32 ,
divisor : i32 ,
}
// This function should calculate `a` divided by `b` if `a` is
// evenly divisible by b.
// Otherwise, it should return a suitable error.
pub fn divide ( a : i32 , b : i32 ) -> Result < i32 , DivisionError > {
}
#[ cfg(test) ]
mod tests {
use super ::* ;
// Tests that verify your `divide` function implementation
#[ 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 ) ) ;
}
// Iterator exercises using your `divide` function
/*
#[ test ]
fn result_with_list ( ) {
let numbers = vec! [ 27 , 297 , 38502 , 81 ] ;
let division_results = numbers . into_iter ( ) . map ( | n | divide ( n , 27 ) ) ;
let x //... Fill in here!
assert_eq! ( format! ( "{:?}" , x ) , "Ok([1, 11, 1426, 3])" ) ;
}
#[ test ]
fn list_of_results ( ) {
let numbers = vec! [ 27 , 297 , 38502 , 81 ] ;
let division_results = numbers . into_iter ( ) . map ( | n | divide ( n , 27 ) ) ;
let x //... Fill in here!
assert_eq! ( format! ( "{:?}" , x ) , "[Ok(1), Ok(11), Ok(1426), Ok(3)]" ) ;
}
* /
}
// Minor hint: In each of the two cases in the match in main, you can create x with either a 'turbofish' or by hinting the type of x to the compiler. You may try both.
// Major hint: Have a look at the Iter trait and at the explanation of its collect function. Especially the part about Result is interesting.