[Browser plugin] playwright run-server is never killed on Debian/Ubuntu (/bin/sh = dash): orphaned node process after every run, terminal hangs when output is piped

[likemusic]

Description

After every pest run that includes browser tests, the playwright run-server node process
survives the pest process on Debian/Ubuntu-based environments (including Laravel Sail
runtimes). One orphan is leaked per run.

The most visible symptom: when pest output is piped (pest ... 2>&1 | cat, CI log
collectors, etc.), the terminal hangs forever after the final test summary — the orphaned
server inherits the stdout pipe, so the reader never gets EOF. Without a pipe the prompt
returns, but orphaned node processes silently accumulate until the machine/container is
restarted.

Environment

• pest-plugin-browser v4.3.1 (the relevant code is unchanged in 4.x HEAD)
• pest 4.x, PHP 8.3 (NTS), Laravel Sail runtime 8.3 (Ubuntu, /bin/sh → dash)
• playwright 1.59.x, Chromium headless
• Not reproducible on macOS (see root cause — that's why it is easy to miss upstream)

Root cause

ServerManager::playwright() builds the server command as a string and
PlaywrightNpmServer::start() runs it via Process::fromShellCommandline(). A string
command goes through proc_open → /bin/sh -c '...', and Symfony Process only prepends
exec for array commandlines — not for fromShellCommandline().

On Debian/Ubuntu /bin/sh is dash, which does not exec-replace itself with a single
-c command. The resulting process tree is:

php (pest)
 └─ sh -c ./node_modules/.bin/playwright run-server ...    ← Symfony Process child (getPid())
     └─ node ./node_modules/.bin/playwright run-server ... ← the actual server

PlaywrightNpmServer::stop() calls $process->stop(timeout: 0.1, signal: SIGTERM), which
signals only the direct child (sh). sh dies, the node server is reparented to PID 1
and keeps running forever. (The node process itself handles SIGTERM fine — killing it
directly works instantly.)

On macOS /bin/sh is bash, which does exec-replace a single -c command, so the signal
reaches node directly and everything shuts down cleanly — the bug is invisible there.

Standalone reproduction (no pest involved)

<?php
require __DIR__.'/vendor/autoload.php';

use Symfony\Component\Process\Process;

$process = Process::fromShellCommandline(
    './node_modules/.bin/playwright run-server --host 127.0.0.1 --port 59999 --mode launchServer',
    getcwd(),
    ['APP_URL' => 'http://127.0.0.1:59999'],
);
$process->setTimeout(0);
$process->start();
$process->waitUntil(fn ($type, $output) => str_contains($output, 'Listening on'));

echo 'symfony getPid(): '.$process->getPid().PHP_EOL;
system("ps -ef --forest | grep -E 'playwright|php' | grep -v grep");

$process->stop(0.1, SIGTERM); // exactly what PlaywrightNpmServer::stop() does

usleep(700000);
system("pgrep -af 'playwright run-server' || echo 'no survivors'");

Observed output on Ubuntu (/bin/sh → dash):

symfony getPid(): 29995
php repro.php
 \_ sh -c ./node_modules/.bin/playwright run-server --host 127.0.0.1 --port 59999 --mode launchServer
 |   \_ node ./node_modules/.bin/playwright run-server --host 127.0.0.1 --port 59999 --mode launchServer
29996 node ./node_modules/.bin/playwright run-server --host 127.0.0.1 --port 59999 --mode launchServer   ← survivor

Suggested fix (verified)

Prepend exec to the shell command in ServerManager::playwright() (non-Windows):

'exec .'.DIRECTORY_SEPARATOR.'node_modules'.DIRECTORY_SEPARATOR.'.bin'.DIRECTORY_SEPARATOR.'playwright run-server --host %s --port %d --mode launchServer',

With exec, sh replaces itself with node, getPid() points at the server itself, and
stop() kills it reliably. Verified with the repro above — the tree collapses to
php → node and no survivors remain after stop(). Also verified end-to-end with a real
browser test run: the terminal returns immediately even with piped output, and
pgrep -af 'playwright run-server' is clean afterwards.

Alternatively, use the array form of Process (no shell at all). Two smaller related
observations spotted while debugging this:

• PlaywrightNpmServer::stop() passes SIGTERM as the fallback signal of
  Process::stop(), so it never escalates to SIGKILL; passing null (default SIGKILL)
  would be more robust.
• Plugin::terminate() swallows the Revolt Error («Must call resume() or throw() before
  calling suspend() again») with an early return before stopping the playwright server —
  if that path is ever taken, the server would leak even with the signal fix.