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 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240
//! Utilities for capture output from tests run in a child process
use crate::{
errors::CollectTestOutputError,
reporter::{heuristic_extract_description, DescriptionKind},
runner::ExecutionResult,
};
use bstr::{ByteSlice, Lines};
use bytes::{Bytes, BytesMut};
use std::{borrow::Cow, sync::OnceLock};
use tokio::io::BufReader;
/// The strategy used to capture test executable output
#[derive(Copy, Clone, PartialEq, Default, Debug)]
pub enum CaptureStrategy {
/// Captures `stdout` and `stderr` separately
///
/// * pro: output from `stdout` and `stderr` can be identified and easily split
/// * con: ordering between the streams cannot be guaranteed
#[default]
Split,
/// Captures `stdout` and `stderr` in a single stream
///
/// * pro: output is guaranteed to be ordered as it would in a terminal emulator
/// * con: distinction between `stdout` and `stderr` is lost, all output is attributed to `stdout`
Combined,
/// Output is not captured
///
/// This mode is used when using --no-capture, causing nextest to execute
/// tests serially without capturing output
None,
}
/// A single output for a test.
///
/// This is a wrapper around a [`Bytes`] that provides some convenience methods.
#[derive(Clone, Debug)]
pub struct TestSingleOutput {
/// The raw output buffer
pub buf: Bytes,
/// A string representation of the output, computed on first access.
///
/// `None` means the output is valid UTF-8.
as_str: OnceLock<Option<Box<str>>>,
}
impl From<Bytes> for TestSingleOutput {
#[inline]
fn from(buf: Bytes) -> Self {
Self {
buf,
as_str: OnceLock::new(),
}
}
}
impl TestSingleOutput {
/// Gets this output as a lossy UTF-8 string.
#[inline]
pub fn as_str_lossy(&self) -> &str {
let s = self
.as_str
.get_or_init(|| match String::from_utf8_lossy(&self.buf) {
// A borrowed string from `from_utf8_lossy` is always valid UTF-8. We can't store
// the `Cow` directly because that would be a self-referential struct. (Well, we
// could via a library like ouroboros, but that's really unnecessary.)
Cow::Borrowed(_) => None,
Cow::Owned(s) => Some(s.into_boxed_str()),
});
match s {
Some(s) => s,
// SAFETY: Immediately above, we've established that `None` means `buf` is valid UTF-8.
None => unsafe { std::str::from_utf8_unchecked(&self.buf) },
}
}
/// Iterates over lines in this output.
#[inline]
pub fn lines(&self) -> Lines<'_> {
self.buf.lines()
}
/// Returns true if the output is empty.
#[inline]
pub fn is_empty(&self) -> bool {
self.buf.is_empty()
}
}
/// The complete captured output of a child process.
#[derive(Clone, Debug)]
pub enum TestExecutionOutput {
/// The process was run and the output was captured.
Output(TestOutput),
/// There was an execution failure.
ExecFail {
/// A single-line message.
message: String,
/// The full description, including other errors, to print out.
description: String,
},
}
/// The output of a test.
///
/// Part of [`TestExecutionOutput`].
#[derive(Clone, Debug)]
pub enum TestOutput {
/// The output was split into stdout and stderr.
Split {
/// The captured stdout.
stdout: TestSingleOutput,
/// The captured stderr.
stderr: TestSingleOutput,
},
/// The output was combined into stdout and stderr.
Combined {
/// The captured output.
output: TestSingleOutput,
},
}
impl TestOutput {
/// Attempts to extract a description of a test failure from the output of the test.
pub fn heuristic_extract_description(
&self,
exec_result: ExecutionResult,
) -> Option<DescriptionKind<'_>> {
match self {
Self::Split { stdout, stderr } => {
if let Some(kind) =
heuristic_extract_description(exec_result, &stdout.buf, &stderr.buf)
{
return Some(kind);
}
}
Self::Combined { output } => {
if let Some(kind) =
heuristic_extract_description(exec_result, &output.buf, &output.buf)
{
return Some(kind);
}
}
}
None
}
}
/// The size of each buffered reader's buffer, and the size at which we grow
/// the interleaved buffer.
///
/// This size is not totally arbitrary, but rather the (normal) page size on
/// most linux, windows, and macos systems.
const CHUNK_SIZE: usize = 4 * 1024;
/// Collects the stdout and/or stderr streams into a single buffer
pub async fn collect_test_output(
streams: Option<crate::test_command::Output>,
) -> Result<Option<TestOutput>, CollectTestOutputError> {
use tokio::io::AsyncBufReadExt as _;
let Some(output) = streams else {
return Ok(None);
};
match output {
crate::test_command::Output::Split { stdout, stderr } => {
let mut stdout = BufReader::with_capacity(CHUNK_SIZE, stdout);
let mut stderr = BufReader::with_capacity(CHUNK_SIZE, stderr);
let mut stdout_acc = BytesMut::with_capacity(CHUNK_SIZE);
let mut stderr_acc = BytesMut::with_capacity(CHUNK_SIZE);
let mut out_done = false;
let mut err_done = false;
loop {
tokio::select! {
res = stdout.fill_buf(), if !out_done => {
let read = {
let buf = res.map_err(CollectTestOutputError::ReadStdout)?;
stdout_acc.extend_from_slice(buf);
buf.len()
};
stdout.consume(read);
out_done = read == 0;
}
res = stderr.fill_buf(), if !err_done => {
let read = {
let buf = res.map_err(CollectTestOutputError::ReadStderr)?;
stderr_acc.extend_from_slice(buf);
buf.len()
};
stderr.consume(read);
err_done = read == 0;
}
else => break,
};
}
Ok(Some(TestOutput::Split {
stdout: stdout_acc.freeze().into(),
stderr: stderr_acc.freeze().into(),
}))
}
crate::test_command::Output::Combined(output) => {
let mut output = BufReader::with_capacity(CHUNK_SIZE, output);
let mut acc = BytesMut::with_capacity(CHUNK_SIZE);
loop {
let read = {
let buf = output
.fill_buf()
.await
.map_err(CollectTestOutputError::ReadStdout)?;
acc.extend_from_slice(buf);
buf.len()
};
output.consume(read);
if read == 0 {
break;
}
}
Ok(Some(TestOutput::Combined {
output: acc.freeze().into(),
}))
}
}
}