Documentation Tests

Rust has built-in support for documentation tests:

#![allow(unused)]
fn main() {
/// Shortens a string to the given length.
///
/// ```
/// use playground::shorten_string;
/// assert_eq!(shorten_string("Hello World", 5), "Hello");
/// assert_eq!(shorten_string("Hello World", 20), "Hello World");
/// ```
pub fn shorten_string(s: &str, length: usize) -> &str {
    &s[..std::cmp::min(length, s.len())]
}
}

• Code blocks in /// comments are automatically seen as Rust code.
• The code will be compiled and executed as part of cargo test.
• Test the above code on the Rust Playground.

pub fn shorten_string(s: &str, length: usize) -> &str {
    &s[..std::cmp::min(length, s.len())]
}

#[test]
fn test_single_word() {
    assert_eq!(shorten_string("Hello World",5), "Hello");
}

#[test]
fn test_multiple_words() {
    assert_eq!(shorten_string("Hello World",20), "Hello World");
}