反向的字符串

例如:

• input: “cool”
• output: “looc”

用这个字符串:uüu测试你的函数, 看会发生什么。试着写一个函数,这恰当地反转这个字符串。提示: {grapheme clusters}

要拿到加分，需要测试加分项, 从最后一个测试中移除(#[ignore])标志),并运行下面测试命令:

$ cargo test --features grapheme

Introductory challenge to reverse an input string https://medium.freecodecamp.org/how-to-reverse-a-string-in-javascript-in-3-different-ways-75e4763c68cb

pub fn reverse(input: &str) -> String {
   unimplemented!("Write a function to reverse {}", input);
}

# #![allow(unused_variables)]
#fn main() {
/// Tests for reverse-string
///
/// Generated by [script][script] using [canonical data][canonical-data]
///
/// [script]: https://github.com/exercism/rust/blob/master/bin/init_exercise.py
/// [canonical-data]: https://raw.githubusercontent.com/exercism/problem-specifications/master/exercises/reverse-string/canonical_data.json

/// Process a single test case for the property `reverse`
fn process_reverse_case(input: &str, expected: &str) {
   assert_eq!(&reverse(input), expected)
}

#[test]
/// empty string
fn test_empty_string() {
   process_reverse_case("", "");
}

#[test]
//#[ignore]
/// a word
fn test_a_word() {
   process_reverse_case("robot", "tobor");
}

#[test]
//#[ignore]
/// a capitalized word
fn test_a_capitalized_word() {
   process_reverse_case("Ramen", "nemaR");
}

#[test]
//#[ignore]
/// a sentence with punctuation
fn test_a_sentence_with_punctuation() {
   process_reverse_case("I'm hungry!", "!yrgnuh m'I");
}

#[test]
//#[ignore]
/// a palindrome
fn test_a_palindrome() {
   process_reverse_case("racecar", "racecar");
}

#[test]
//#[ignore]
/// wide characters
fn test_wide_characters() {
   process_reverse_case("子猫", "猫子");
}

#[test]
//#[ignore]
#[cfg(feature = "grapheme")]
/// grapheme clusters
fn test_grapheme_clusters() {
   process_reverse_case("uüu", "uüu");
}

#}

# #![allow(unused_variables)]
#fn main() {
//! Example implementation for reverse-string

pub fn reverse(input: &str) -> String {
   let mut output = String::with_capacity(input.len());
   output.extend(input.chars().rev());
   output
}

#}