rustdis 0.1.1

A partial Redis server implementation intended purely for educational purposes
Documentation 
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use std::sync::{Arc, Mutex};

use crate::commands::executable::Executable;
use crate::commands::CommandParser;
use crate::frame::Frame;
use crate::store::Store;
use crate::Error;

/// Decrements the number stored at key by one.
///
/// Ref: <https://redis.io/docs/latest/commands/decr/>
#[derive(Debug, PartialEq)]
pub struct Decr {
    pub key: String,
}

impl Executable for Decr {
    fn exec(self, store: Arc<Mutex<Store>>) -> Result<Frame, Error> {
        let res = store.lock().unwrap().incr_by(&self.key, -1);

        match res {
            Ok(_) => Ok(Frame::Simple("OK".to_string())),
            Err(msg) => Ok(Frame::Error(msg.to_string())),
        }
    }
}

impl TryFrom<&mut CommandParser> for Decr {
    type Error = Error;

    fn try_from(parser: &mut CommandParser) -> Result<Self, Self::Error> {
        let key = parser.next_string()?;

        Ok(Self { key })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::commands::Command;
    use bytes::Bytes;

    #[test]
    fn existing_key() {
        let frame = Frame::Array(vec![
            Frame::Bulk(Bytes::from("DECR")),
            Frame::Bulk(Bytes::from("key1")),
        ]);
        let cmd = Command::try_from(frame).unwrap();

        assert_eq!(
            cmd,
            Command::Decr(Decr {
                key: "key1".to_string()
            })
        );

        let store = Arc::new(Mutex::new(Store::new()));
        {
            let mut store = store.lock().unwrap();
            store.set(String::from("key1"), Bytes::from("1"));
        }

        let result = cmd.exec(store.clone()).unwrap();

        assert_eq!(result, Frame::Simple("OK".to_string()));

        assert_eq!(store.lock().unwrap().get("key1"), Some(&Bytes::from("0")));
    }

    #[test]
    fn non_existing_key() {
        let frame = Frame::Array(vec![
            Frame::Bulk(Bytes::from("DECR")),
            Frame::Bulk(Bytes::from("key1")),
        ]);
        let cmd = Command::try_from(frame).unwrap();

        assert_eq!(
            cmd,
            Command::Decr(Decr {
                key: "key1".to_string()
            })
        );

        let store = Arc::new(Mutex::new(Store::new()));

        let result = cmd.exec(store.clone()).unwrap();

        assert_eq!(result, Frame::Simple("OK".to_string()));

        assert_eq!(store.lock().unwrap().get("key1"), Some(&Bytes::from("-1")));
    }

    #[test]
    fn invalid_key_type() {
        let frame = Frame::Array(vec![
            Frame::Bulk(Bytes::from("DECR")),
            Frame::Bulk(Bytes::from("key1")),
        ]);
        let cmd = Command::try_from(frame).unwrap();

        assert_eq!(
            cmd,
            Command::Decr(Decr {
                key: "key1".to_string()
            })
        );

        let store = Arc::new(Mutex::new(Store::new()));
        {
            let mut store = store.lock().unwrap();
            store.set(String::from("key1"), Bytes::from("value"));
        }

        let result = cmd.exec(store.clone()).unwrap();

        assert_eq!(
            result,
            Frame::Error("value is not of the correct type or out of range".to_string())
        );

        assert_eq!(
            store.lock().unwrap().get("key1"),
            Some(&Bytes::from("value"))
        );
    }

    #[test]
    fn out_of_range() {
        let frame = Frame::Array(vec![
            Frame::Bulk(Bytes::from("DECR")),
            Frame::Bulk(Bytes::from("key1")),
        ]);
        let cmd = Command::try_from(frame).unwrap();

        assert_eq!(
            cmd,
            Command::Decr(Decr {
                key: "key1".to_string()
            })
        );

        let store = Arc::new(Mutex::new(Store::new()));
        {
            let mut store = store.lock().unwrap();
            store.set(String::from("key1"), Bytes::from("999223372036854775808"));
        }

        let result = cmd.exec(store.clone()).unwrap();

        assert_eq!(
            result,
            Frame::Error("value is not of the correct type or out of range".to_string())
        );

        assert_eq!(
            store.lock().unwrap().get("key1"),
            Some(&Bytes::from("999223372036854775808"))
        );
    }
}