Chapter 12, Section 4. Copy button of Listing 12-16 includes code from Lisiting 12-15

[2ak]

In section 12.4, copy and paste of Listing 12-16 includes code from Listing 12-15.
Current result of copy paste:

use std::error::Error;
use std::fs;

pub struct Config {
    pub query: String,
    pub filename: String,
}

impl Config {
    pub fn new(args: &[String]) -> Result<Config, &str> {
        if args.len() < 3 {
            return Err("not enough arguments");
        }

        let query = args[1].clone();
        let filename = args[2].clone();

        Ok(Config { query, filename })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;

    Ok(())
}

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    vec![]
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn one_result() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";

        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
    }
}

Pasted result for Listing 12-16 should be:

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    vec![]
}

[carols10cents]

This is how mdbook works with hidden code; please see rust-lang/mdBook#712 for discussion of whether this is how it should work or not. Thanks!