Hi,

this small patch series fixes another instance of broken TAP output that has landed via 4d11b9c218 (Merge branch 'pt/fsmonitor-linux', 2026-05-31).

As this has happened multiple times by now I decided to have a look at whether we can fix this class of issues a bit more holistically. So this series also contains a change that makes prove bail out when it sees invalid TAP output, which uncovers a small set of preexisting issues in our test suite.

Changes in v2:
  - Fix waiting for p4d, and deduplicate the logic that does this.
  - Link to v1: https://patch.msgid.link/20260602-pks-t7527-fix-tap-output-v1-0-db3da2a1b137@pks.im

Thanks!

Patrick

---
Patrick Steinhardt (4):
      t7527: fix broken TAP output
      t/test-lib: silence EBUSY errors on Windows during test cleanup
      t/lib-git-p4: silence output when killing p4d and its watchdog
      t: let prove fail when parsing invalid TAP output

 t/lib-git-p4.sh              |  4 ++--
 t/t7527-builtin-fsmonitor.sh |  7 ++++---
 t/test-lib.sh                | 10 ++++++++--
 3 files changed, 14 insertions(+), 7 deletions(-)

Range-diff versus v1:

1: 09977059d1 = 1: 18b4fc7b81 t7527: fix broken TAP output 2: 162d3d42d8 = 2: 8dd921534b t/test-lib: silence EBUSY errors on Windows during test cleanup 3: 4ecb8cb1ce < -: ---------- t/lib-git-p4: silence output when killing p4d and its watchdog -: ---------- > 3: 8b343176fe t/lib-git-p4: silence output when killing p4d and its watchdog 4: 95fb0d07ae = 4: e69aa0ab79 t: let prove fail when parsing invalid TAP output

--- base-commit: 1666c1265231b0bc5f613fbbf3f0a9896cdef76e change-id: 20260601-pks-t7527-fix-tap-output-105da1d73df0

Before running the tests in t7527 we first verify whether the fsmonitor even works, which seems to depend on the actual filesystem that is in use. The verification executes outside of any prerequisite or test body, so its stdout/stderr is not being redirected.

The consequence of this is that any command that prints to stdout/stderr may break the TAP specification by printing invalid lines. And in fact we already do that, as git-init(1) prints the path to the created Git repository by default.

Fix this issue by moving the logic into a lazy prerequisite.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 t/t7527-builtin-fsmonitor.sh | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

When tests have finished we clean up the trash directory via `rm -rf`. On Windows this can fail with EBUSY in cases where a process still holds some of the files open, for example when we have spawned a daemonized process that wasn't properly terminated. We thus retry several times, but every failure will result in error messages being printed, and that in turn breaks the TAP output format.

One such case where this is causing issues is in t921x, which contains tests related to Scalar. Some tests spawn the fsmonitor daemon, and we never properly terminate it.

The obvious fix would be to ensure that we never leak any processes, but that gets ugly fast. Instead, let's work around the issue by silencing error messages printed by the `rm -rf` calls. We already know to print an error when the retry loop fails, so we don't loose much.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 t/test-lib.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

When stopping the p4d watchdog process via "kill -9", the shell may print a job-control notification like:

  ./test-lib.sh: line 1269: 57960 Killed: 9               while true; do
      if test $nr_tries_left -eq 0; then
          kill -9 $p4d_pid; exit 1;
      fi; sleep 1; nr_tries_left=$(($nr_tries_left - 1));
  done 2> /dev/null 4>&2  (wd: ~)

This message is printed asynchronously by the shell when it reaps the process. While harmless right now, this will cause breakage once we enable strict parsing of the TAP protocol in a subsequent commit.

Fix this by using `wait` so that we can synchronously reap the watchdog process and swallow the diagnostic.

While at it, deduplicate the logic we have in `stop_p4d_and_watchdog ()` and `stop_and_cleanup_p4d ()`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 t/lib-git-p4.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

To make the result of our tests accessible we use the TAP protocol. This protocol is parsed by either prove or by Meson. Unfortunately, these two tools differ when it comes to their strictness when parsing the protocol:

  - Prove by default happily accepts lines not specified by the
    protocol.

  - Meson will also accept such lines, but prints a big and ugly warning
    message.

We have fixed our test suite in the past to not print invalid TAP lines anymore via b1dc2e796e (Merge branch 'ps/meson-tap-parse', 2025-06-17). But as none of our tools perform a strict check it's still possible for broken tests to sneak back in, like for example in 362f69547f (Merge branch 'ps/t1006-tap-fix', 2025-07-16). This doesn't hurt at all when using prove, but it's quite annoying when using Meson due to the generated warnings.

Unfortunately, there doesn't seem to be a portable way to make all tools complain about violations of the TAP format. The TAP 14 specification has added pragmas to the protocol that would allow us to say `pragma +strict`, and the effect of that would be to treat invalid TAP lines as a test failure. But the release of TAP 14 is still rather recent, and Test-Harness for example only gained support for it in version 3.48, which was released in 2023.

In fact though, this pragma was already introduced as an inofficial extension of the TAP protocol with Test-Harness 3.10, released in 2008. So while not all tools understand the pragma, at least prove does for a long time.

Unconditionally enable the pragma when using prove so that we'll detect tests that emit broken TAP output right away. This would have detected the issues fixed in preceding commits:

    $ prove t7527-builtin-fsmonitor.sh
    t7527-builtin-fsmonitor.sh .. All 69 subtests passed
            (less 6 skipped subtests: 63 okay)

    Test Summary Report
    -------------------
    t7527-builtin-fsmonitor.sh (Wstat: 0 Tests: 69 Failed: 0)
      Parse errors: Unknown TAP token: "Initialized empty Git repository in /tmp/git/test_fsmonitor_smoke/.git/"

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 t/test-lib.sh | 6 ++++++
 1 file changed, 6 insertions(+)