01_engine-xfread flakes on a SIGPIPE race under pipefail#637
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The test matched engine output with `echo "$out" | grep -q PATTERN`. Under
`set -o pipefail`, grep -q exits the moment it matches, so echo takes a SIGPIPE
writing the rest and the pipeline reports failure even though the pattern was
found. The `|| { echo FAIL; exit 1; }` guard then fired on a passing case,
turning it into an intermittent, output-size-dependent failure (seen on the
Debian buildd leg of #632).
Match with here-strings instead, dropping the pipe and the race entirely.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>
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The test matched engine output with
echo "$out" | grep -q PATTERN. Underset -o pipefail,grep -qexits the moment it matches, soechotakes a SIGPIPE writing the rest of its output and the pipeline reports failure even though the pattern was found. The|| { echo FAIL; exit 1; }guard then fired on a passing assertion, so the test failed intermittently depending on output size and scheduling. It showed up on the Debian buildd leg of #632, a PR that does not touch this code.Switching the three matches to here-strings (
grep -q PATTERN <<<"$out") drops the pipe, so there is no early reader to SIGPIPE the writer. A deterministic control confirms the mechanism: the old form exits 141 when grep matches the first of many lines, the here-string form exits 0. The fixed test ran 200 times with no failures.Pre-existing flake, independent of the batch fixes, so it gets its own PR.