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Diffstat (limited to 'library/std/src/io/buffered/tests.rs')
| -rw-r--r-- | library/std/src/io/buffered/tests.rs | 916 |
1 files changed, 916 insertions, 0 deletions
diff --git a/library/std/src/io/buffered/tests.rs b/library/std/src/io/buffered/tests.rs new file mode 100644 index 00000000000..1cd02ee299a --- /dev/null +++ b/library/std/src/io/buffered/tests.rs @@ -0,0 +1,916 @@ +use crate::io::prelude::*; +use crate::io::{self, BufReader, BufWriter, ErrorKind, IoSlice, LineWriter, SeekFrom}; +use crate::sync::atomic::{AtomicUsize, Ordering}; +use crate::thread; + +/// A dummy reader intended at testing short-reads propagation. +pub struct ShortReader { + lengths: Vec<usize>, +} + +// FIXME: rustfmt and tidy disagree about the correct formatting of this +// function. This leads to issues for users with editors configured to +// rustfmt-on-save. +impl Read for ShortReader { + fn read(&mut self, _: &mut [u8]) -> io::Result<usize> { + if self.lengths.is_empty() { Ok(0) } else { Ok(self.lengths.remove(0)) } + } +} + +#[test] +fn test_buffered_reader() { + let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; + let mut reader = BufReader::with_capacity(2, inner); + + let mut buf = [0, 0, 0]; + let nread = reader.read(&mut buf); + assert_eq!(nread.unwrap(), 3); + assert_eq!(buf, [5, 6, 7]); + assert_eq!(reader.buffer(), []); + + let mut buf = [0, 0]; + let nread = reader.read(&mut buf); + assert_eq!(nread.unwrap(), 2); + assert_eq!(buf, [0, 1]); + assert_eq!(reader.buffer(), []); + + let mut buf = [0]; + let nread = reader.read(&mut buf); + assert_eq!(nread.unwrap(), 1); + assert_eq!(buf, [2]); + assert_eq!(reader.buffer(), [3]); + + let mut buf = [0, 0, 0]; + let nread = reader.read(&mut buf); + assert_eq!(nread.unwrap(), 1); + assert_eq!(buf, [3, 0, 0]); + assert_eq!(reader.buffer(), []); + + let nread = reader.read(&mut buf); + assert_eq!(nread.unwrap(), 1); + assert_eq!(buf, [4, 0, 0]); + assert_eq!(reader.buffer(), []); + + assert_eq!(reader.read(&mut buf).unwrap(), 0); +} + +#[test] +fn test_buffered_reader_seek() { + let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; + let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner)); + + assert_eq!(reader.seek(SeekFrom::Start(3)).ok(), Some(3)); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); + assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(3)); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); + assert_eq!(reader.seek(SeekFrom::Current(1)).ok(), Some(4)); + assert_eq!(reader.fill_buf().ok(), Some(&[1, 2][..])); + reader.consume(1); + assert_eq!(reader.seek(SeekFrom::Current(-2)).ok(), Some(3)); +} + +#[test] +fn test_buffered_reader_seek_relative() { + let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; + let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner)); + + assert!(reader.seek_relative(3).is_ok()); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); + assert!(reader.seek_relative(0).is_ok()); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); + assert!(reader.seek_relative(1).is_ok()); + assert_eq!(reader.fill_buf().ok(), Some(&[1][..])); + assert!(reader.seek_relative(-1).is_ok()); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); + assert!(reader.seek_relative(2).is_ok()); + assert_eq!(reader.fill_buf().ok(), Some(&[2, 3][..])); +} + +#[test] +fn test_buffered_reader_invalidated_after_read() { + let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; + let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner)); + + assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..])); + reader.consume(3); + + let mut buffer = [0, 0, 0, 0, 0]; + assert_eq!(reader.read(&mut buffer).ok(), Some(5)); + assert_eq!(buffer, [0, 1, 2, 3, 4]); + + assert!(reader.seek_relative(-2).is_ok()); + let mut buffer = [0, 0]; + assert_eq!(reader.read(&mut buffer).ok(), Some(2)); + assert_eq!(buffer, [3, 4]); +} + +#[test] +fn test_buffered_reader_invalidated_after_seek() { + let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; + let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner)); + + assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..])); + reader.consume(3); + + assert!(reader.seek(SeekFrom::Current(5)).is_ok()); + + assert!(reader.seek_relative(-2).is_ok()); + let mut buffer = [0, 0]; + assert_eq!(reader.read(&mut buffer).ok(), Some(2)); + assert_eq!(buffer, [3, 4]); +} + +#[test] +fn test_buffered_reader_seek_underflow() { + // gimmick reader that yields its position modulo 256 for each byte + struct PositionReader { + pos: u64, + } + impl Read for PositionReader { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + let len = buf.len(); + for x in buf { + *x = self.pos as u8; + self.pos = self.pos.wrapping_add(1); + } + Ok(len) + } + } + impl Seek for PositionReader { + fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { + match pos { + SeekFrom::Start(n) => { + self.pos = n; + } + SeekFrom::Current(n) => { + self.pos = self.pos.wrapping_add(n as u64); + } + SeekFrom::End(n) => { + self.pos = u64::MAX.wrapping_add(n as u64); + } + } + Ok(self.pos) + } + } + + let mut reader = BufReader::with_capacity(5, PositionReader { pos: 0 }); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 1, 2, 3, 4][..])); + assert_eq!(reader.seek(SeekFrom::End(-5)).ok(), Some(u64::MAX - 5)); + assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5)); + // the following seek will require two underlying seeks + let expected = 9223372036854775802; + assert_eq!(reader.seek(SeekFrom::Current(i64::MIN)).ok(), Some(expected)); + assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5)); + // seeking to 0 should empty the buffer. + assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(expected)); + assert_eq!(reader.get_ref().pos, expected); +} + +#[test] +fn test_buffered_reader_seek_underflow_discard_buffer_between_seeks() { + // gimmick reader that returns Err after first seek + struct ErrAfterFirstSeekReader { + first_seek: bool, + } + impl Read for ErrAfterFirstSeekReader { + fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { + for x in &mut *buf { + *x = 0; + } + Ok(buf.len()) + } + } + impl Seek for ErrAfterFirstSeekReader { + fn seek(&mut self, _: SeekFrom) -> io::Result<u64> { + if self.first_seek { + self.first_seek = false; + Ok(0) + } else { + Err(io::Error::new(io::ErrorKind::Other, "oh no!")) + } + } + } + + let mut reader = BufReader::with_capacity(5, ErrAfterFirstSeekReader { first_seek: true }); + assert_eq!(reader.fill_buf().ok(), Some(&[0, 0, 0, 0, 0][..])); + + // The following seek will require two underlying seeks. The first will + // succeed but the second will fail. This should still invalidate the + // buffer. + assert!(reader.seek(SeekFrom::Current(i64::MIN)).is_err()); + assert_eq!(reader.buffer().len(), 0); +} + +#[test] +fn test_buffered_writer() { + let inner = Vec::new(); + let mut writer = BufWriter::with_capacity(2, inner); + + writer.write(&[0, 1]).unwrap(); + assert_eq!(writer.buffer(), []); + assert_eq!(*writer.get_ref(), [0, 1]); + + writer.write(&[2]).unwrap(); + assert_eq!(writer.buffer(), [2]); + assert_eq!(*writer.get_ref(), [0, 1]); + + writer.write(&[3]).unwrap(); + assert_eq!(writer.buffer(), [2, 3]); + assert_eq!(*writer.get_ref(), [0, 1]); + + writer.flush().unwrap(); + assert_eq!(writer.buffer(), []); + assert_eq!(*writer.get_ref(), [0, 1, 2, 3]); + + writer.write(&[4]).unwrap(); + writer.write(&[5]).unwrap(); + assert_eq!(writer.buffer(), [4, 5]); + assert_eq!(*writer.get_ref(), [0, 1, 2, 3]); + + writer.write(&[6]).unwrap(); + assert_eq!(writer.buffer(), [6]); + assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]); + + writer.write(&[7, 8]).unwrap(); + assert_eq!(writer.buffer(), []); + assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]); + + writer.write(&[9, 10, 11]).unwrap(); + assert_eq!(writer.buffer(), []); + assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]); + + writer.flush().unwrap(); + assert_eq!(writer.buffer(), []); + assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]); +} + +#[test] +fn test_buffered_writer_inner_flushes() { + let mut w = BufWriter::with_capacity(3, Vec::new()); + w.write(&[0, 1]).unwrap(); + assert_eq!(*w.get_ref(), []); + let w = w.into_inner().unwrap(); + assert_eq!(w, [0, 1]); +} + +#[test] +fn test_buffered_writer_seek() { + let mut w = BufWriter::with_capacity(3, io::Cursor::new(Vec::new())); + w.write_all(&[0, 1, 2, 3, 4, 5]).unwrap(); + w.write_all(&[6, 7]).unwrap(); + assert_eq!(w.seek(SeekFrom::Current(0)).ok(), Some(8)); + assert_eq!(&w.get_ref().get_ref()[..], &[0, 1, 2, 3, 4, 5, 6, 7][..]); + assert_eq!(w.seek(SeekFrom::Start(2)).ok(), Some(2)); + w.write_all(&[8, 9]).unwrap(); + assert_eq!(&w.into_inner().unwrap().into_inner()[..], &[0, 1, 8, 9, 4, 5, 6, 7]); +} + +#[test] +fn test_read_until() { + let inner: &[u8] = &[0, 1, 2, 1, 0]; + let mut reader = BufReader::with_capacity(2, inner); + let mut v = Vec::new(); + reader.read_until(0, &mut v).unwrap(); + assert_eq!(v, [0]); + v.truncate(0); + reader.read_until(2, &mut v).unwrap(); + assert_eq!(v, [1, 2]); + v.truncate(0); + reader.read_until(1, &mut v).unwrap(); + assert_eq!(v, [1]); + v.truncate(0); + reader.read_until(8, &mut v).unwrap(); + assert_eq!(v, [0]); + v.truncate(0); + reader.read_until(9, &mut v).unwrap(); + assert_eq!(v, []); +} + +#[test] +fn test_line_buffer() { + let mut writer = LineWriter::new(Vec::new()); + writer.write(&[0]).unwrap(); + assert_eq!(*writer.get_ref(), []); + writer.write(&[1]).unwrap(); + assert_eq!(*writer.get_ref(), []); + writer.flush().unwrap(); + assert_eq!(*writer.get_ref(), [0, 1]); + writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap(); + assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n']); + writer.flush().unwrap(); + assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2]); + writer.write(&[3, b'\n']).unwrap(); + assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n']); +} + +#[test] +fn test_read_line() { + let in_buf: &[u8] = b"a\nb\nc"; + let mut reader = BufReader::with_capacity(2, in_buf); + let mut s = String::new(); + reader.read_line(&mut s).unwrap(); + assert_eq!(s, "a\n"); + s.truncate(0); + reader.read_line(&mut s).unwrap(); + assert_eq!(s, "b\n"); + s.truncate(0); + reader.read_line(&mut s).unwrap(); + assert_eq!(s, "c"); + s.truncate(0); + reader.read_line(&mut s).unwrap(); + assert_eq!(s, ""); +} + +#[test] +fn test_lines() { + let in_buf: &[u8] = b"a\nb\nc"; + let reader = BufReader::with_capacity(2, in_buf); + let mut it = reader.lines(); + assert_eq!(it.next().unwrap().unwrap(), "a".to_string()); + assert_eq!(it.next().unwrap().unwrap(), "b".to_string()); + assert_eq!(it.next().unwrap().unwrap(), "c".to_string()); + assert!(it.next().is_none()); +} + +#[test] +fn test_short_reads() { + let inner = ShortReader { lengths: vec![0, 1, 2, 0, 1, 0] }; + let mut reader = BufReader::new(inner); + let mut buf = [0, 0]; + assert_eq!(reader.read(&mut buf).unwrap(), 0); + assert_eq!(reader.read(&mut buf).unwrap(), 1); + assert_eq!(reader.read(&mut buf).unwrap(), 2); + assert_eq!(reader.read(&mut buf).unwrap(), 0); + assert_eq!(reader.read(&mut buf).unwrap(), 1); + assert_eq!(reader.read(&mut buf).unwrap(), 0); + assert_eq!(reader.read(&mut buf).unwrap(), 0); +} + +#[test] +#[should_panic] +fn dont_panic_in_drop_on_panicked_flush() { + struct FailFlushWriter; + + impl Write for FailFlushWriter { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + Ok(buf.len()) + } + fn flush(&mut self) -> io::Result<()> { + Err(io::Error::last_os_error()) + } + } + + let writer = FailFlushWriter; + let _writer = BufWriter::new(writer); + + // If writer panics *again* due to the flush error then the process will + // abort. + panic!(); +} + +#[test] +#[cfg_attr(target_os = "emscripten", ignore)] +fn panic_in_write_doesnt_flush_in_drop() { + static WRITES: AtomicUsize = AtomicUsize::new(0); + + struct PanicWriter; + + impl Write for PanicWriter { + fn write(&mut self, _: &[u8]) -> io::Result<usize> { + WRITES.fetch_add(1, Ordering::SeqCst); + panic!(); + } + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } + } + + thread::spawn(|| { + let mut writer = BufWriter::new(PanicWriter); + let _ = writer.write(b"hello world"); + let _ = writer.flush(); + }) + .join() + .unwrap_err(); + + assert_eq!(WRITES.load(Ordering::SeqCst), 1); +} + +#[bench] +fn bench_buffered_reader(b: &mut test::Bencher) { + b.iter(|| BufReader::new(io::empty())); +} + +#[bench] +fn bench_buffered_writer(b: &mut test::Bencher) { + b.iter(|| BufWriter::new(io::sink())); +} + +/// A simple `Write` target, designed to be wrapped by `LineWriter` / +/// `BufWriter` / etc, that can have its `write` & `flush` behavior +/// configured +#[derive(Default, Clone)] +struct ProgrammableSink { + // Writes append to this slice + pub buffer: Vec<u8>, + + // Flush sets this flag + pub flushed: bool, + + // If true, writes will always be an error + pub always_write_error: bool, + + // If true, flushes will always be an error + pub always_flush_error: bool, + + // If set, only up to this number of bytes will be written in a single + // call to `write` + pub accept_prefix: Option<usize>, + + // If set, counts down with each write, and writes return an error + // when it hits 0 + pub max_writes: Option<usize>, + + // If set, attempting to write when max_writes == Some(0) will be an + // error; otherwise, it will return Ok(0). + pub error_after_max_writes: bool, +} + +impl Write for ProgrammableSink { + fn write(&mut self, data: &[u8]) -> io::Result<usize> { + if self.always_write_error { + return Err(io::Error::new(io::ErrorKind::Other, "test - always_write_error")); + } + + match self.max_writes { + Some(0) if self.error_after_max_writes => { + return Err(io::Error::new(io::ErrorKind::Other, "test - max_writes")); + } + Some(0) => return Ok(0), + Some(ref mut count) => *count -= 1, + None => {} + } + + let len = match self.accept_prefix { + None => data.len(), + Some(prefix) => data.len().min(prefix), + }; + + let data = &data[..len]; + self.buffer.extend_from_slice(data); + + Ok(len) + } + + fn flush(&mut self) -> io::Result<()> { + if self.always_flush_error { + Err(io::Error::new(io::ErrorKind::Other, "test - always_flush_error")) + } else { + self.flushed = true; + Ok(()) + } + } +} + +/// Previously the `LineWriter` could successfully write some bytes but +/// then fail to report that it has done so. Additionally, an erroneous +/// flush after a successful write was permanently ignored. +/// +/// Test that a line writer correctly reports the number of written bytes, +/// and that it attempts to flush buffered lines from previous writes +/// before processing new data +/// +/// Regression test for #37807 +#[test] +fn erroneous_flush_retried() { + let writer = ProgrammableSink { + // Only write up to 4 bytes at a time + accept_prefix: Some(4), + + // Accept the first two writes, then error the others + max_writes: Some(2), + error_after_max_writes: true, + + ..Default::default() + }; + + // This should write the first 4 bytes. The rest will be buffered, out + // to the last newline. + let mut writer = LineWriter::new(writer); + assert_eq!(writer.write(b"a\nb\nc\nd\ne").unwrap(), 8); + + // This write should attempt to flush "c\nd\n", then buffer "e". No + // errors should happen here because no further writes should be + // attempted against `writer`. + assert_eq!(writer.write(b"e").unwrap(), 1); + assert_eq!(&writer.get_ref().buffer, b"a\nb\nc\nd\n"); +} + +#[test] +fn line_vectored() { + let mut a = LineWriter::new(Vec::new()); + assert_eq!( + a.write_vectored(&[ + IoSlice::new(&[]), + IoSlice::new(b"\n"), + IoSlice::new(&[]), + IoSlice::new(b"a"), + ]) + .unwrap(), + 2, + ); + assert_eq!(a.get_ref(), b"\n"); + + assert_eq!( + a.write_vectored(&[ + IoSlice::new(&[]), + IoSlice::new(b"b"), + IoSlice::new(&[]), + IoSlice::new(b"a"), + IoSlice::new(&[]), + IoSlice::new(b"c"), + ]) + .unwrap(), + 3, + ); + assert_eq!(a.get_ref(), b"\n"); + a.flush().unwrap(); + assert_eq!(a.get_ref(), b"\nabac"); + assert_eq!(a.write_vectored(&[]).unwrap(), 0); + assert_eq!( + a.write_vectored(&[ + IoSlice::new(&[]), + IoSlice::new(&[]), + IoSlice::new(&[]), + IoSlice::new(&[]), + ]) + .unwrap(), + 0, + ); + assert_eq!(a.write_vectored(&[IoSlice::new(b"a\nb"),]).unwrap(), 3); + assert_eq!(a.get_ref(), b"\nabaca\nb"); +} + +#[test] +fn line_vectored_partial_and_errors() { + use crate::collections::VecDeque; + + enum Call { + Write { inputs: Vec<&'static [u8]>, output: io::Result<usize> }, + Flush { output: io::Result<()> }, + } + + #[derive(Default)] + struct Writer { + calls: VecDeque<Call>, + } + + impl Write for Writer { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.write_vectored(&[IoSlice::new(buf)]) + } + + fn write_vectored(&mut self, buf: &[IoSlice<'_>]) -> io::Result<usize> { + match self.calls.pop_front().expect("unexpected call to write") { + Call::Write { inputs, output } => { + assert_eq!(inputs, buf.iter().map(|b| &**b).collect::<Vec<_>>()); + output + } + Call::Flush { .. } => panic!("unexpected call to write; expected a flush"), + } + } + + fn is_write_vectored(&self) -> bool { + true + } + + fn flush(&mut self) -> io::Result<()> { + match self.calls.pop_front().expect("Unexpected call to flush") { + Call::Flush { output } => output, + Call::Write { .. } => panic!("unexpected call to flush; expected a write"), + } + } + } + + impl Drop for Writer { + fn drop(&mut self) { + if !thread::panicking() { + assert_eq!(self.calls.len(), 0); + } + } + } + + // partial writes keep going + let mut a = LineWriter::new(Writer::default()); + a.write_vectored(&[IoSlice::new(&[]), IoSlice::new(b"abc")]).unwrap(); + + a.get_mut().calls.push_back(Call::Write { inputs: vec![b"abc"], output: Ok(1) }); + a.get_mut().calls.push_back(Call::Write { inputs: vec![b"bc"], output: Ok(2) }); + a.get_mut().calls.push_back(Call::Write { inputs: vec![b"x", b"\n"], output: Ok(2) }); + + a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\n")]).unwrap(); + + a.get_mut().calls.push_back(Call::Flush { output: Ok(()) }); + a.flush().unwrap(); + + // erroneous writes stop and don't write more + a.get_mut().calls.push_back(Call::Write { inputs: vec![b"x", b"\na"], output: Err(err()) }); + a.get_mut().calls.push_back(Call::Flush { output: Ok(()) }); + assert!(a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\na")]).is_err()); + a.flush().unwrap(); + + fn err() -> io::Error { + io::Error::new(io::ErrorKind::Other, "x") + } +} + +/// Test that, in cases where vectored writing is not enabled, the +/// LineWriter uses the normal `write` call, which more-correctly handles +/// partial lines +#[test] +fn line_vectored_ignored() { + let writer = ProgrammableSink::default(); + let mut writer = LineWriter::new(writer); + + let content = [ + IoSlice::new(&[]), + IoSlice::new(b"Line 1\nLine"), + IoSlice::new(b" 2\nLine 3\nL"), + IoSlice::new(&[]), + IoSlice::new(&[]), + IoSlice::new(b"ine 4"), + IoSlice::new(b"\nLine 5\n"), + ]; + + let count = writer.write_vectored(&content).unwrap(); + assert_eq!(count, 11); + assert_eq!(&writer.get_ref().buffer, b"Line 1\n"); + + let count = writer.write_vectored(&content[2..]).unwrap(); + assert_eq!(count, 11); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n"); + + let count = writer.write_vectored(&content[5..]).unwrap(); + assert_eq!(count, 5); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n"); + + let count = writer.write_vectored(&content[6..]).unwrap(); + assert_eq!(count, 8); + assert_eq!( + writer.get_ref().buffer.as_slice(), + b"Line 1\nLine 2\nLine 3\nLine 4\nLine 5\n".as_ref() + ); +} + +/// Test that, given this input: +/// +/// Line 1\n +/// Line 2\n +/// Line 3\n +/// Line 4 +/// +/// And given a result that only writes to midway through Line 2 +/// +/// That only up to the end of Line 3 is buffered +/// +/// This behavior is desirable because it prevents flushing partial lines +#[test] +fn partial_write_buffers_line() { + let writer = ProgrammableSink { accept_prefix: Some(13), ..Default::default() }; + let mut writer = LineWriter::new(writer); + + assert_eq!(writer.write(b"Line 1\nLine 2\nLine 3\nLine4").unwrap(), 21); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2"); + + assert_eq!(writer.write(b"Line 4").unwrap(), 6); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\n"); +} + +/// Test that, given this input: +/// +/// Line 1\n +/// Line 2\n +/// Line 3 +/// +/// And given that the full write of lines 1 and 2 was successful +/// That data up to Line 3 is buffered +#[test] +fn partial_line_buffered_after_line_write() { + let writer = ProgrammableSink::default(); + let mut writer = LineWriter::new(writer); + + assert_eq!(writer.write(b"Line 1\nLine 2\nLine 3").unwrap(), 20); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\n"); + + assert!(writer.flush().is_ok()); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3"); +} + +/// Test that, given a partial line that exceeds the length of +/// LineBuffer's buffer (that is, without a trailing newline), that that +/// line is written to the inner writer +#[test] +fn long_line_flushed() { + let writer = ProgrammableSink::default(); + let mut writer = LineWriter::with_capacity(5, writer); + + assert_eq!(writer.write(b"0123456789").unwrap(), 10); + assert_eq!(&writer.get_ref().buffer, b"0123456789"); +} + +/// Test that, given a very long partial line *after* successfully +/// flushing a complete line, that that line is buffered unconditionally, +/// and no additional writes take place. This assures the property that +/// `write` should make at-most-one attempt to write new data. +#[test] +fn line_long_tail_not_flushed() { + let writer = ProgrammableSink::default(); + let mut writer = LineWriter::with_capacity(5, writer); + + // Assert that Line 1\n is flushed, and 01234 is buffered + assert_eq!(writer.write(b"Line 1\n0123456789").unwrap(), 12); + assert_eq!(&writer.get_ref().buffer, b"Line 1\n"); + + // Because the buffer is full, this subsequent write will flush it + assert_eq!(writer.write(b"5").unwrap(), 1); + assert_eq!(&writer.get_ref().buffer, b"Line 1\n01234"); +} + +/// Test that, if an attempt to pre-flush buffered data returns Ok(0), +/// this is propagated as an error. +#[test] +fn line_buffer_write0_error() { + let writer = ProgrammableSink { + // Accept one write, then return Ok(0) on subsequent ones + max_writes: Some(1), + + ..Default::default() + }; + let mut writer = LineWriter::new(writer); + + // This should write "Line 1\n" and buffer "Partial" + assert_eq!(writer.write(b"Line 1\nPartial").unwrap(), 14); + assert_eq!(&writer.get_ref().buffer, b"Line 1\n"); + + // This will attempt to flush "partial", which will return Ok(0), which + // needs to be an error, because we've already informed the client + // that we accepted the write. + let err = writer.write(b" Line End\n").unwrap_err(); + assert_eq!(err.kind(), ErrorKind::WriteZero); + assert_eq!(&writer.get_ref().buffer, b"Line 1\n"); +} + +/// Test that, if a write returns Ok(0) after a successful pre-flush, this +/// is propagated as Ok(0) +#[test] +fn line_buffer_write0_normal() { + let writer = ProgrammableSink { + // Accept two writes, then return Ok(0) on subsequent ones + max_writes: Some(2), + + ..Default::default() + }; + let mut writer = LineWriter::new(writer); + + // This should write "Line 1\n" and buffer "Partial" + assert_eq!(writer.write(b"Line 1\nPartial").unwrap(), 14); + assert_eq!(&writer.get_ref().buffer, b"Line 1\n"); + + // This will flush partial, which will succeed, but then return Ok(0) + // when flushing " Line End\n" + assert_eq!(writer.write(b" Line End\n").unwrap(), 0); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nPartial"); +} + +/// LineWriter has a custom `write_all`; make sure it works correctly +#[test] +fn line_write_all() { + let writer = ProgrammableSink { + // Only write 5 bytes at a time + accept_prefix: Some(5), + ..Default::default() + }; + let mut writer = LineWriter::new(writer); + + writer.write_all(b"Line 1\nLine 2\nLine 3\nLine 4\nPartial").unwrap(); + assert_eq!(&writer.get_ref().buffer, b"Line 1\nLine 2\nLine 3\nLine 4\n"); + writer.write_all(b" Line 5\n").unwrap(); + assert_eq!( + writer.get_ref().buffer.as_slice(), + b"Line 1\nLine 2\nLine 3\nLine 4\nPartial Line 5\n".as_ref(), + ); +} + +#[test] +fn line_write_all_error() { + let writer = ProgrammableSink { + // Only accept up to 3 writes of up to 5 bytes each + accept_prefix: Some(5), + max_writes: Some(3), + ..Default::default() + }; + + let mut writer = LineWriter::new(writer); + let res = writer.write_all(b"Line 1\nLine 2\nLine 3\nLine 4\nPartial"); + assert!(res.is_err()); + // An error from write_all leaves everything in an indeterminate state, + // so there's nothing else to test here +} + +/// Under certain circumstances, the old implementation of LineWriter +/// would try to buffer "to the last newline" but be forced to buffer +/// less than that, leading to inappropriate partial line writes. +/// Regression test for that issue. +#[test] +fn partial_multiline_buffering() { + let writer = ProgrammableSink { + // Write only up to 5 bytes at a time + accept_prefix: Some(5), + ..Default::default() + }; + + let mut writer = LineWriter::with_capacity(10, writer); + + let content = b"AAAAABBBBB\nCCCCDDDDDD\nEEE"; + + // When content is written, LineWriter will try to write blocks A, B, + // C, and D. Only block A will succeed. Under the old behavior, LineWriter + // would then try to buffer B, C and D, but because its capacity is 10, + // it will only be able to buffer B and C. We don't want to buffer + // partial lines concurrent with whole lines, so the correct behavior + // is to buffer only block B (out to the newline) + assert_eq!(writer.write(content).unwrap(), 11); + assert_eq!(writer.get_ref().buffer, *b"AAAAA"); + + writer.flush().unwrap(); + assert_eq!(writer.get_ref().buffer, *b"AAAAABBBBB\n"); +} + +/// Same as test_partial_multiline_buffering, but in the event NO full lines +/// fit in the buffer, just buffer as much as possible +#[test] +fn partial_multiline_buffering_without_full_line() { + let writer = ProgrammableSink { + // Write only up to 5 bytes at a time + accept_prefix: Some(5), + ..Default::default() + }; + + let mut writer = LineWriter::with_capacity(5, writer); + + let content = b"AAAAABBBBBBBBBB\nCCCCC\nDDDDD"; + + // When content is written, LineWriter will try to write blocks A, B, + // and C. Only block A will succeed. Under the old behavior, LineWriter + // would then try to buffer B and C, but because its capacity is 5, + // it will only be able to buffer part of B. Because it's not possible + // for it to buffer any complete lines, it should buffer as much of B as + // possible + assert_eq!(writer.write(content).unwrap(), 10); + assert_eq!(writer.get_ref().buffer, *b"AAAAA"); + + writer.flush().unwrap(); + assert_eq!(writer.get_ref().buffer, *b"AAAAABBBBB"); +} + +#[derive(Debug, Clone, PartialEq, Eq)] +enum RecordedEvent { + Write(String), + Flush, +} + +#[derive(Debug, Clone, Default)] +struct WriteRecorder { + pub events: Vec<RecordedEvent>, +} + +impl Write for WriteRecorder { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + use crate::str::from_utf8; + + self.events.push(RecordedEvent::Write(from_utf8(buf).unwrap().to_string())); + Ok(buf.len()) + } + + fn flush(&mut self) -> io::Result<()> { + self.events.push(RecordedEvent::Flush); + Ok(()) + } +} + +/// Test that a normal, formatted writeln only results in a single write +/// call to the underlying writer. A naive implementation of +/// LineWriter::write_all results in two writes: one of the buffered data, +/// and another of the final substring in the formatted set +#[test] +fn single_formatted_write() { + let writer = WriteRecorder::default(); + let mut writer = LineWriter::new(writer); + + // Under a naive implementation of LineWriter, this will result in two + // writes: "hello, world" and "!\n", because write() has to flush the + // buffer before attempting to write the last "!\n". write_all shouldn't + // have this limitation. + writeln!(&mut writer, "{}, {}!", "hello", "world").unwrap(); + assert_eq!(writer.get_ref().events, [RecordedEvent::Write("hello, world!\n".to_string())]); +} |