io_read_to_string.rs

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#![warn(rust_2018_idioms)]

#![cfg(feature = "full")]

use std::io;

use tokio::io::AsyncReadExt;

use tokio_test::assert_ok;

use tokio_test::io::Builder;

#[tokio::test]

async fn read_to_string() {

    let mut buf = String::new();

    let mut rd: &[u8] = b"hello world";

    let n = assert_ok!(rd.read_to_string(&mut buf).await);

    assert_eq!(n, 11);

    assert_eq!(buf[..], "hello world"[..]);

#[tokio::test]

async fn to_string_does_not_truncate_on_utf8_error() {

    let data = vec![0xff, 0xff, 0xff];

    let mut s = "abc".to_string();

    match AsyncReadExt::read_to_string(&mut data.as_slice(), &mut s).await {

        Ok(len) => panic!("Should fail: {} bytes.", len),

        Err(err) if err.to_string() == "stream did not contain valid UTF-8" => {}

        Err(err) => panic!("Fail: {}.", err),

    assert_eq!(s, "abc");

#[tokio::test]

async fn to_string_does_not_truncate_on_io_error() {

    let mut mock = Builder::new()

        .read(b"def")

        .read_error(io::Error::new(io::ErrorKind::Other, "whoops"))

        .build();

    let mut s = "abc".to_string();

    match AsyncReadExt::read_to_string(&mut mock, &mut s).await {

        Ok(len) => panic!("Should fail: {} bytes.", len),

        Err(err) if err.to_string() == "whoops" => {}

        Err(err) => panic!("Fail: {}.", err),

    assert_eq!(s, "abc");

#[tokio::test]

async fn to_string_appends() {

    let data = b"def".to_vec();

    let mut s = "abc".to_string();

    let len = AsyncReadExt::read_to_string(&mut data.as_slice(), &mut s)

        .await

        .unwrap();

    assert_eq!(len, 3);

    assert_eq!(s, "abcdef");