Struct mockstream::FailingMockStream

pub struct FailingMockStream { /* fields omitted */ }

FailingMockStream mocks a stream which will fail upon read or write

Examples

use std::io::{Cursor, Read};

struct CountIo {}

impl CountIo {
    fn read_data(&self, r: &mut Read) -> usize {
        let mut count: usize = 0;
        let mut retries = 3;

        loop {
            let mut buffer = [0; 5];
            match r.read(&mut buffer) {
                Err(_) => {
                    if retries == 0 { break; }
                    retries -= 1;
                },
                Ok(0) => break,
                Ok(n) => count += n,
            }
        }
        count
    }
}

#[test]
fn test_io_retries() {
    let mut c = Cursor::new(&b"1234"[..])
            .chain(FailingMockStream::new(ErrorKind::Other, "Failing", 3))
            .chain(Cursor::new(&b"5678"[..]));

    let sut = CountIo {};
    // this will fail unless read_data performs at least 3 retries on I/O errors
    assert_eq!(8, sut.read_data(&mut c));
}

Methods

impl FailingMockStream

fn new(
    kind: ErrorKind,
    message: &'static str,
    repeat_count: i32
) -> FailingMockStream

Creates a FailingMockStream

When read or write is called, it will return an error repeat_count times. kind and message can be specified to define the exact error.

Trait Implementations

impl Clone for FailingMockStream

fn clone(&self) -> FailingMockStream

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Read for FailingMockStream

fn read(&mut self, _: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

unsafe fn initializer(&self) -> Initializer

🔬 This is a nightly-only experimental API. (read_initializer)

Determines if this Reader can work with buffers of uninitialized memory.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf.

fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

Transforms this Read instance to an [Iterator] over its bytes.

fn chars(self) -> Chars<Self>

🔬 This is a nightly-only experimental API. (io)

the semantics of a partial read/write of where errors happen is currently unclear and may change

Transforms this Read instance to an [Iterator] over [char]s.

fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read, 

Creates an adaptor which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

Creates an adaptor which will read at most limit bytes from it.

impl Write for FailingMockStream

fn write(&mut self, _: &[u8]) -> Result<usize>

Write a buffer into this object, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this write.

fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

Creates a "by reference" adaptor for this instance of Write.