micro-tower 0.1.0

micro-tower is a framework to generate and manage micro services.
Documentation 
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#![feature(error_reporter)]

use std::cmp::min;
use std::io::ErrorKind;
use std::num::ParseIntError;
use std::pin::Pin;
use std::task::{Context, Poll};

use bytes::{BufMut, BytesMut};
use micro_tower::api::codec;
use micro_tower::prelude::ServiceBuilderExt;
use micro_tower::shutdown::Controller;
use micro_tower::ServiceBuilder;
use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};

struct Stream {
    input: String,
    ipos: usize,
    output: BytesMut,
}

impl Stream {
    pub fn from_input(input: impl Into<String>) -> Self {
        Self {
            input: input.into(),
            ipos: 0,
            output: BytesMut::new(),
        }
    }
}

impl AsyncRead for Stream {
    fn poll_read(
        mut self: Pin<&mut Self>,
        _cx: &mut Context<'_>,
        buf: &mut ReadBuf<'_>,
    ) -> Poll<std::io::Result<()>> {
        if self.ipos < self.input.len() {
            let count = min(buf.remaining(), self.input.len() - self.ipos);
            buf.put_slice(&self.input.as_bytes()[self.ipos..self.ipos + count]);
            self.ipos += count;
            Poll::Ready(Ok(()))
        } else {
            Poll::Ready(Err(std::io::Error::new(
                ErrorKind::UnexpectedEof,
                "Buffer Empty",
            )))
        }
    }
}
impl AsyncWrite for Stream {
    fn poll_write(
        mut self: Pin<&mut Self>,
        _cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<Result<usize, std::io::Error>> {
        self.output.put_slice(buf);
        Poll::Ready(Ok(buf.len()))
    }

    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), std::io::Error>> {
        Poll::Ready(Ok(()))
    }

    fn poll_shutdown(
        self: Pin<&mut Self>,
        _cx: &mut Context<'_>,
    ) -> Poll<Result<(), std::io::Error>> {
        Poll::Ready(Ok(()))
    }
}

#[micro_tower::codegen::service]
async fn parse(input: String) -> Result<i32, ParseIntError> {
    input.parse()
}

#[tokio::test]
async fn parse_stream_test() {
    let service = parse::builder().build();
    let service = ServiceBuilder::new()
        .api::<String, codec::Json>()
        .service(service);
    let stream = Stream::from_input(r#""42""#);
    let controller = Controller::default();

    if let Err(err) = micro_tower::session::stream::spawn_fut(stream, service, controller).await {
        if let Some(err) = err.downcast_ref::<std::io::Error>() {
            assert_eq!(err.kind(), ErrorKind::UnexpectedEof);
            assert_eq!(format!("{err}"), "Buffer Empty");
        } else {
            let report = micro_tower::report!(err.as_ref());
            panic!("{report:?}")
        }
    }
}

#[tokio::test]
async fn parse_stream_err_test() {
    let service = parse::builder().build();
    let service = ServiceBuilder::new()
        .api::<String, codec::Json>()
        .service(service);
    let stream = Stream::from_input(r#""test""#);
    let controller = Controller::default();

    if let Err(err) = micro_tower::session::stream::spawn_fut(stream, service, controller).await {
        if let Some(err) = err.downcast_ref::<std::io::Error>() {
            assert_eq!(err.kind(), ErrorKind::UnexpectedEof);
            assert_eq!(format!("{err}"), "Buffer Empty");
        } else {
            let report = micro_tower::report!(err.as_ref());
            panic!("Expected parse int error but got: {report:?}")
        }
    }
}

#[tokio::test]
async fn parse_stream_bad_request() {
    let service = parse::builder().build();
    let service = ServiceBuilder::new()
        .api::<String, codec::Json>()
        .service(service);
    let stream = Stream::from_input(r#"test"#);
    let controller = Controller::default();

    if let Err(err) = micro_tower::session::stream::spawn_fut(stream, service, controller).await {
        if let Some(err) = err.downcast_ref::<std::io::Error>() {
            assert_eq!(err.kind(), ErrorKind::UnexpectedEof);
            assert_eq!(format!("{err}"), "Buffer Empty");
        } else {
            let report = micro_tower::report!(err.as_ref());
            panic!("Expected parse int error but got: {report:?}")
        }
    }
}