1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::fmt;
use std::io::{self, Error, Write, sink};
struct ErrorDisplay;
impl fmt::Display for ErrorDisplay {
fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
Err(fmt::Error)
}
}
struct ErrorWriter;
const FORMAT_ERROR: io::ErrorKind = io::ErrorKind::Other;
const WRITER_ERROR: io::ErrorKind = io::ErrorKind::NotConnected;
impl Write for ErrorWriter {
fn write(&mut self, _buf: &[u8]) -> io::Result<usize> {
Err(Error::new(WRITER_ERROR, "not connected"))
}
fn flush(&mut self) -> io::Result<()> { Ok(()) }
}
fn main() {
// Test that the error from the formatter is propagated.
let res = write!(sink(), "{} {} {}", 1, ErrorDisplay, "bar");
assert!(res.is_err(), "formatter error did not propagate");
assert_eq!(res.unwrap_err().kind(), FORMAT_ERROR);
// Test that an underlying error is propagated
let res = write!(ErrorWriter, "abc");
assert!(res.is_err(), "writer error did not propagate");
// Writer error
let res = write!(ErrorWriter, "abc {}", ErrorDisplay);
assert!(res.is_err(), "writer error did not propagate");
assert_eq!(res.unwrap_err().kind(), WRITER_ERROR);
// Formatter error
let res = write!(ErrorWriter, "{} abc", ErrorDisplay);
assert!(res.is_err(), "formatter error did not propagate");
assert_eq!(res.unwrap_err().kind(), FORMAT_ERROR);
}
|
