For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
Given a list of inputs, generate the relevant proverb. For example, given the list ["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]
, you will output the full text of this proverbial rhyme:
For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a nail.
Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content. No line of the output text should be a static, unchanging string; all should vary according to the input given.
Refer to the exercism help page for Rust installation and learning resources.
Execute the tests with:
$ cargo test
All but the first test have been ignored. After you get the first test to
pass, open the tests source file which is located in the tests
directory
and remove the #[ignore]
flag from the next test and get the tests to pass
again. Each separate test is a function with #[test]
flag above it.
Continue, until you pass every test.
If you wish to run all tests without editing the tests source file, use:
$ cargo test -- --ignored
To run a specific test, for example some_test
, you can use:
$ cargo test some_test
If the specific test is ignored use:
$ cargo test some_test -- --ignored
To learn more about Rust tests refer to the online test documentation
Make sure to read the Modules chapter if you haven't already, it will help you with organizing your files.
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Wikipedia http://en.wikipedia.org/wiki/For_Want_of_a_Nail
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
use proverb::build_proverb;
#[test]
fn test_two_pieces() {
let input = vec!["nail", "shoe"];
let expected = vec![
"For want of a nail the shoe was lost.",
"And all for the want of a nail.",
]
.join("\n");
assert_eq!(build_proverb(&input), expected);
}
// Notice the change in the last line at three pieces.
#[test]
#[ignore]
fn test_three_pieces() {
let input = vec!["nail", "shoe", "horse"];
let expected = vec![
"For want of a nail the shoe was lost.",
"For want of a shoe the horse was lost.",
"And all for the want of a nail.",
]
.join("\n");
assert_eq!(build_proverb(&input), expected);
}
#[test]
#[ignore]
fn test_one_piece() {
let input = vec!["nail"];
let expected = String::from("And all for the want of a nail.");
assert_eq!(build_proverb(&input), expected);
}
#[test]
#[ignore]
fn test_zero_pieces() {
let input: Vec<&str> = vec![];
let expected = String::new();
assert_eq!(build_proverb(&input), expected);
}
#[test]
#[ignore]
fn test_full() {
let input = vec![
"nail", "shoe", "horse", "rider", "message", "battle", "kingdom",
];
let expected = vec![
"For want of a nail the shoe was lost.",
"For want of a shoe the horse was lost.",
"For want of a horse the rider was lost.",
"For want of a rider the message was lost.",
"For want of a message the battle was lost.",
"For want of a battle the kingdom was lost.",
"And all for the want of a nail.",
]
.join("\n");
assert_eq!(build_proverb(&input), expected);
}
#[test]
#[ignore]
fn test_three_pieces_modernized() {
let input = vec!["pin", "gun", "soldier", "battle"];
let expected = vec![
"For want of a pin the gun was lost.",
"For want of a gun the soldier was lost.",
"For want of a soldier the battle was lost.",
"And all for the want of a pin.",
]
.join("\n");
assert_eq!(build_proverb(&input), expected);
}
pub fn build_proverb(list: &[&str]) -> String {
let mut ans = String::new();
if list.is_empty() {
return ans;
}
for i in 0..(list.len() - 1) {
let first = list[i];
let second = list[i + 1];
ans += &format!("For want of a {} the {} was lost.\n", first, second);
}
ans += &format!("And all for the want of a {}.", list[0]);
ans
}
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.
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