Rust kata

rust-kata.rs

// KATA
#![feature(convert)] 

use std::result::Result as StdResult;
use std::io;
use std::process::Command;
use std::path::{Path,PathBuf};
use std::error::Error;
use std::ffi::OsStr;
use std::fmt;

#[derive(Debug)]
enum GitCommandError {
    Unknown,
    Status(i32), // process exit status <> 0
    ExecCommand(io::Error), // cause
}

impl fmt::Display  for GitCommandError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.description().fmt(f)
    }
}

impl Error for GitCommandError {
    fn description(&self) -> &str {
        match *self {
            GitCommandError::Unknown => "Unknown error",
            GitCommandError::Status(_) => "Status error",
            GitCommandError::ExecCommand(_) => "Exec command failed",
        }
    }

    fn cause(&self) -> Option<&Error> {
        match *self {
            GitCommandError::ExecCommand( ref ioe ) => Some(ioe),
            _ => None,
        }
    }
}

impl From<io::Error> for GitCommandError {
    fn from(cause : io::Error) -> Self {
        GitCommandError::ExecCommand(cause)
    }
}


type Result<T> = StdResult<T, GitCommandError>;

fn git_exec<S: AsRef<OsStr>>(dir: &Path, args: &[S]) -> Result<String> {
    let output = try!(
        Command::new(&PathBuf::from("git"))
            .current_dir(dir)
            .args(args)
            .output()
        );

    if !output.status.success() {
        Err( GitCommandError::Status(output.status.code().unwrap()) )
    } else {
        let out = String::from_utf8_lossy(&output.stdout);
        Ok(String::from(&*out))
    }
}

fn main() {
    println!("git -> {:?}", git_exec(&PathBuf::from("."), vec!["log"].as_slice()));
}

Part of http://www.meetup.com/Latvian-Developers-Network/events/221757301/

It appears the error during the KATA was cause by the following

λ ~/personal/rust-kata/ master* git log
fatal: bad default revision 'HEAD'
λ ~/personal/rust-kata/ master*

😊 other than works as intended without any changes