PING-PONG

Gear is very easy to write code for!

This is the minimal program for a classic ping-pong contract:

#![no_std]

use gstd::{debug, msg, prelude::*};

static mut MESSAGE_LOG: Vec<String> = vec![];

#[no_mangle]
pub unsafe extern "C" fn handle() {
    let new_msg = String::from_utf8(msg::load_bytes()).expect("Invalid message");

    if new_msg == "PING" {
        msg::reply_bytes("PONG", 0).unwrap();
    }

    MESSAGE_LOG.push(new_msg);

    debug!("{:?} total message(s) stored: ", MESSAGE_LOG.len());

    for log in MESSAGE_LOG.iter() {
        debug!(log);
    }
}

/// and a simple unit test:

#[cfg(test)]
mod tests {
    extern crate std;

    use gtest::{Log, Program, System};

    #[test]
    fn it_works() {
        let system = System::new();
        system.init_logger();

        let program = Program::current(&system);

        let res = program.send_bytes(42, "INIT");
        assert!(res.log().is_empty());

        let res = program.send_bytes(42, "PING");
        let log = Log::builder().source(1).dest(42).payload_bytes("PONG");
        assert!(res.contains(&log));
    }
}

The program just sends PONG back to the original sender who sent PING to it.

GitHub link: https://github.com/gear-dapps/ping