47 lines
1.4 KiB
Rust
47 lines
1.4 KiB
Rust
// run-pass
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use std::fmt;
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use std::io::{self, Error, Write, sink};
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struct ErrorDisplay;
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impl fmt::Display for ErrorDisplay {
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fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
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Err(fmt::Error)
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}
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}
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struct ErrorWriter;
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const FORMAT_ERROR: io::ErrorKind = io::ErrorKind::Other;
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const WRITER_ERROR: io::ErrorKind = io::ErrorKind::NotConnected;
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impl Write for ErrorWriter {
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fn write(&mut self, _buf: &[u8]) -> io::Result<usize> {
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Err(Error::new(WRITER_ERROR, "not connected"))
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}
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fn flush(&mut self) -> io::Result<()> { Ok(()) }
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}
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fn main() {
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// Test that the error from the formatter is propagated.
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let res = write!(sink(), "{} {} {}", 1, ErrorDisplay, "bar");
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assert!(res.is_err(), "formatter error did not propagate");
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assert_eq!(res.unwrap_err().kind(), FORMAT_ERROR);
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// Test that an underlying error is propagated
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let res = write!(ErrorWriter, "abc");
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assert!(res.is_err(), "writer error did not propagate");
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// Writer error
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let res = write!(ErrorWriter, "abc {}", ErrorDisplay);
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assert!(res.is_err(), "writer error did not propagate");
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assert_eq!(res.unwrap_err().kind(), WRITER_ERROR);
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// Formatter error
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let res = write!(ErrorWriter, "{} abc", ErrorDisplay);
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assert!(res.is_err(), "formatter error did not propagate");
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assert_eq!(res.unwrap_err().kind(), FORMAT_ERROR);
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}
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