Brad Fitzpatrick 95d874e9b4 cmd/testwrapper: surface race reports and skip retries when detected
A data race in a package matters more than any individual test
result. Two related problems:

1. Where go test's race detector text ("WARNING: DATA RACE" plus
   the goroutine stack traces) lands in JSON output is timing-
   dependent: it can be attributed to a test that ends up reporting
   PASS (e.g. when the racing goroutines outlive the test that
   spawned them and TSan prints during a different test's window).
   testwrapper's main loop only flushes the logs of failed tests,
   so the race report ends up stuck in a passing test's buffer and
   is silently dropped. The race builders just see a bare
   "FAIL\nFAIL\tpkg\ttime".

2. If the failing test in such a package happens to be marked flaky,
   testwrapper retries it. That is the worst possible response to a
   race: the flaky test might not even be the racy code, and a
   second run without the racy goroutines could "succeed" while
   hiding the real bug.

Address both: scan every output line for the race detector's first-
line marker. Track whether the package observed a race at all, on
the pkgFinished testAttempt. When a race was seen, fold every per-
test log buffer into the package-level logs (so the full report
surfaces from the existing pkg-fail flush path), and drop any
flaky-test retry plans for that package so we fail immediately
instead of running another attempt.

Two new tests:
- TestRaceSuppressesFlakyRetry verifies that a flaky test alongside
  a racy test does NOT get retried.
- TestRaceAttributedToPassingTest verifies that a race attributed by
  test2json to a passing test still surfaces in the output.

Also add a corpus of captured raw test binary outputs under
cmd/testwrapper/testdata/, with one subdirectory per scenario,
documenting the six representative shapes that go test -race can
emit (race in test body, race in goroutines that outlive a test,
race forced into a later test, race in TestMain post-m.Run, and a
parallel-tests split-attribution case via a "=== NAME" redirect
line). See its README.md for details.

Fixes #19603

Change-Id: Ifbfcd67fb3b1882c4907bd9cb2d68a8b5a91dd54
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-05-19 21:21:05 -07:00
2026-05-14 21:04:41 -07:00

Tailscale

https://tailscale.com

Private WireGuard® networks made easy

Overview

This repository contains the majority of Tailscale's open source code. Notably, it includes the tailscaled daemon and the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows, macOS, and to varying degrees on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's code, but this repo doesn't contain the mobile GUI code.

Other Tailscale repos of note:

For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.

Using

We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.

Other clients

The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.

Building

We always require the latest Go release, currently Go 1.26. (While we build releases with our Go fork, its use is not required.)

go install tailscale.com/cmd/tailscale{,d}

If you're packaging Tailscale for distribution, use build_dist.sh instead, to burn commit IDs and version info into the binaries:

./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled

If your distro has conventions that preclude the use of build_dist.sh, please do the equivalent of what it does in your distro's way, so that bug reports contain useful version information.

Bugs

Please file any issues about this code or the hosted service on the issue tracker.

Contributing

PRs welcome! But please file bugs. Commit messages should reference bugs.

We require Developer Certificate of Origin Signed-off-by lines in commits.

See commit-messages.md (or skim git log) for our commit message style.

About Us

Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:

WireGuard is a registered trademark of Jason A. Donenfeld.

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