1 
use std::io;
2 
use std::io::BufRead;
3 

            

        

            

                4
            

            

                
            

            

                
/// Prints a prompt and reads a line of input.

            

        

            

                5
            

            

                2
            

            

                
fn prompt<R>(prompt_text: &str, mut reader: R) -> String

            

        

            

                6
            

            

                2
            

            

                
where

            

        

            

                7
            

            

                2
            

            

                
    R: BufRead,

            

        

            

                8
            

            

                2
            

            

                
{

            

        

            

                9
            

            

                2
            

            

                
    println!("{}", prompt_text);

            

        

            

                10
            

            

                2
            

            

                
    let mut input = String::new();

            

        

            

                11
            

            

                2
            

            

                
    reader.read_line(&mut input).expect("Failed to read input.");

            

        

            

                12
            

            

                2
            

            

                
    input.trim().to_lowercase()

            

        

            

                13
            

            

                2
            

            

                
}

            

        

            

                14
            

            

                
            

            

                

            

        

            

                15
            

            

                
            

            

                
/// Prints a prompt and reads a line of input from stdin.

            

        

            

                16
            

            

                
            

            

                
pub fn prompt_stdin(prompt_text: &str) -> String {

            

        

            

                17
            

            

                
            

            

                
    prompt(prompt_text, io::stdin().lock())

            

        

            

                18
            

            

                
            

            

                
}

            

        

            

                19
            

            

                
            

            

                

            

        

            

                20
            

            

                
            

            

                
#[cfg(test)]

            

        

            

                21
            

            

                
            

            

                
mod tests {

            

        

            

                22
            

            

                
            

            

                
    use super::*;

            

        

            

                23
            

            

                
            

            

                

            

        

            

                24
            

            

                
            

            

                
    #[test]

            

        

            

                25
            

            

                2
            

            

                
    fn test_prompt() {

            

        

            

                26
            

            

                2
            

            

                
        // GIVEN a prompt with expected text

            

        

            

                27
            

            

                2
            

            

                
        let prompt_text = "Enter some text:";

            

        

            

                28
            

            

                2
            

            

                
        let expected = "hello";

            

        

            

                29
            

            

                2
            

            

                
        let reader = std::io::Cursor::new(expected);

            

        

            

                30
            

            

                2
            

            

                

            

        

            

                31
            

            

                2
            

            

                
        // WHEN the user enters text

            

        

            

                32
            

            

                2
            

            

                
        let actual = prompt(prompt_text, reader);

            

        

            

                33
            

            

                2
            

            

                

            

        

            

                34
            

            

                2
            

            

                
        // THEN it should match the expected one

            

        

            

                35
            

            

                2
            

            

                
        assert_eq!(actual, expected);

            

        

            

                36
            

            

                2
            

            

                
    }

            

        

            

                37
            

            

                
            

            

                
}