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PierrunoYTandClaude Opus 5 27b319ca88 test(execution): fail loudly when ps cannot answer instead of skipping (#961)
* test(execution): fail loudly when ps cannot answer instead of skipping

Every test in process_unix_test.go proves something about zombie detection, and
every one of those proofs is read out of ps. When ps could not answer, the
tests skipped — which is indistinguishable from success in CI output — and one
assertion passed vacuously for the same reason. A regression in ps parsing or
availability would have shown up as green.

requireProcessState probes BOTH ps pipelines against this test process, which
is by definition alive and not a zombie, so a working ps must report a live
state for it. When it cannot:

- Under CI (or ZERO_REQUIRE_PS=1) this is a hard failure. ps is present on every
  image used today, so its absence means the pipeline regressed and that has to
  surface immediately.
- Otherwise it stays a skip, so a contributor on an unsupported box is not
  blocked.

Both pipelines are probed because they are deliberately separate: the tests
assert what the production process-table parser concludes, so this file keeps
its own per-PID ps oracle rather than borrowing that parser to establish its own
preconditions. One regression must not be able to silence both sides at once.

Once the probe passes, failing to observe an EXPECTED state is a defect rather
than an environment problem, so the remaining escapes become failures:

- The zombie waits (awaitZombie) fail instead of skipping. The caller never
  waits on the child, so its zombie row persists until reaped — reaching the
  deadline means the child never exited or ps stopped answering, and the two
  are reported distinctly.
- A zombie group that is not signalable fails instead of skipping: a zombie
  still occupies the process table, so if kill(-pid, 0) fails the case under
  test is not present and the assertions after it would prove nothing.
- processSignalTarget returning anything but the individual PID fails instead
  of skipping: the child inherited this process's group, so its PGID is this
  process's PID and can never equal its own PID.

The vacuous assertion in TestTerminateProcessTreeStopsRunningGroup now requires
ok. That is sound rather than merely stricter: the test never waits on the
child, so the group's zombie row must still be present after termination, and
an unknown state means ps stopped answering rather than that the group is
clean.

Verified on Linux (WSL, go1.26.6) rather than by cross-compilation alone:

- all three tests pass unmodified
- with a stub ps that exits 1: CI unset skips with the reason named; CI=true
  fails, naming which pipeline could not answer
- the same broken-ps run against the ORIGINAL file produced two silent skips
  plus one unrelated failure after 12s, versus an immediate, explicit failure now

Windows is unaffected (the file is !windows); go vet passes for linux, darwin
and windows.

Fixes #863

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01U389qmQUhoZB3YtXkFmiTq

* test(execution): treat an unsignalable zombie group as a kernel difference

The macOS Smoke job failed:

    the zombie group 5931 is not signalable (operation not permitted)

That was my error. I converted this skip along with the ps-availability ones,
but it never had anything to do with ps: whether kill(2) may signal a group
whose only member is a zombie is a KERNEL difference. Linux permits it, so
signalTargetRunning goes on to consult ps — the branch this test was written
for. Darwin returns EPERM, so signalTargetRunning short-circuits on the kill and
never reaches ps.

Rather than restore the blanket skip, the test now records which branch answers:

- Signal permitted: assert processGroupHasRunningMember directly, so a ps-side
  regression cannot hide behind the kill result. This is new coverage; the old
  test only checked signalTargetRunning, which conflates the two paths.
- Signal refused: log it and continue.

The outcome assertion — a zombie-only group must not count as running — now runs
on EVERY platform. Previously Darwin skipped before reaching it, so this is
strictly more coverage there, not less.

Any errno other than EPERM still fails: it means the group is not in the state
the test needs, and nothing after it would be meaningful.

TerminateProcessTree is asserted only where the signal is permitted, because
terminateTarget's own kill(2) would hit the same EPERM and return it as a
cleanup error. Worth a maintainer's eye: that may be a real gap in
TerminateProcessTree on such a platform — a zombie-only tree is already exited
and arguably should terminate cleanly rather than report failure, which is the
same spurious-cleanup-failure class #774 set out to remove. Confirming that
needs a Darwin host and is a production change, so it is flagged rather than
guessed at here.

Verified on Linux (WSL, go1.26.6): all three tests pass, including the new
direct ps assertion. The Darwin branch was exercised by forcing the EPERM path
on Linux — it logs both explanations and passes with the outcome assertion
still enforced. go vet passes for linux, darwin and windows.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01U389qmQUhoZB3YtXkFmiTq

---------

Co-authored-by: Claude Opus 5 (1M context) <[email protected]>
2026-08-26 13:22:43 +08:00
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