From 6be1c17bdc511122b1100954374681252c6b851b Mon Sep 17 00:00:00 2001
From: matt <matt@claritum.com>
Date: Wed, 12 Nov 2025 21:58:07 +0000
Subject: [PATCH 1/4] Add failing test for ShutdownHandler with child process

---
 composer.json                                 |  3 ++
 tests/end-to-end/_files/ChildProcessTest.php  | 30 +++++++++++++++++++
 .../end-to-end/cli/child-process-output.phpt  | 23 ++++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 tests/end-to-end/_files/ChildProcessTest.php
 create mode 100644 tests/end-to-end/cli/child-process-output.phpt

diff --git a/composer.json b/composer.json
index 4d443951aa..ab3171616d 100644
--- a/composer.json
+++ b/composer.json
@@ -48,6 +48,9 @@
         "sebastian/version": "^6.0.0",
         "staabm/side-effects-detector": "^1.0.5"
     },
+    "require-dev": {
+        "ext-pcntl": "*"
+    },
     "config": {
         "platform": {
             "php": "8.3.0"
diff --git a/tests/end-to-end/_files/ChildProcessTest.php b/tests/end-to-end/_files/ChildProcessTest.php
new file mode 100644
index 0000000000..bf8270c819
--- /dev/null
+++ b/tests/end-to-end/_files/ChildProcessTest.php
@@ -0,0 +1,30 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture;
+
+use function pcntl_fork;
+use function pcntl_wait;
+use PHPUnit\Framework\TestCase;
+
+final class ChildProcessTest extends TestCase
+{
+    public function testChildProcessOutput(): void
+    {
+        $child = pcntl_fork();
+        $this->assertGreaterThan(-1, $child);
+
+        if ($child) {
+            pcntl_wait($child);
+            $this->assertTrue(true);
+        } else {
+            exit(0);
+        }
+    }
+}
diff --git a/tests/end-to-end/cli/child-process-output.phpt b/tests/end-to-end/cli/child-process-output.phpt
new file mode 100644
index 0000000000..d85e4a1c44
--- /dev/null
+++ b/tests/end-to-end/cli/child-process-output.phpt
@@ -0,0 +1,23 @@
+--TEST--
+ShutdownHandler does not output when child process exits
+--FILE--
+<?php declare(strict_types=1);
+$_SERVER['argv'][] = '--do-not-cache-result';
+$_SERVER['argv'][] = '--no-configuration';
+$_SERVER['argv'][] = '--filter';
+$_SERVER['argv'][] = 'testChildProcessOutput';
+$_SERVER['argv'][] = __DIR__ . '/../_files/ChildProcessTest.php';
+
+require __DIR__ . '/../../bootstrap.php';
+
+(new PHPUnit\TextUI\Application)->run($_SERVER['argv']);
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+Runtime: %s
+
+.                                                                   1 / 1 (100%)
+
+Time: %s, Memory: %s
+
+OK (1 test, 2 assertions)

From 0699696cc9d7dbb11a1f2e026a01ebec06c1917d Mon Sep 17 00:00:00 2001
From: matt <matt@claritum.com>
Date: Wed, 12 Nov 2025 22:06:34 +0000
Subject: [PATCH 2/4] ShutdownHandler does not output in child processes

---
 src/Runner/ShutdownHandler.php | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Runner/ShutdownHandler.php b/src/Runner/ShutdownHandler.php
index faecf088c3..129ec9f868 100644
--- a/src/Runner/ShutdownHandler.php
+++ b/src/Runner/ShutdownHandler.php
@@ -10,6 +10,7 @@
 namespace PHPUnit\Runner;
 
 use const PHP_EOL;
+use function getmypid;
 use function register_shutdown_function;
 use function rtrim;
 
@@ -42,13 +43,14 @@ private static function register(): void
         }
 
         self::$registered = true;
+        $pid              = getmypid();
 
         register_shutdown_function(
-            static function (): void
+            static function () use ($pid): void
             {
                 $message = rtrim(self::$message);
 
-                if ($message === '') {
+                if ($message === '' || $pid !== getmypid()) {
                     return;
                 }
 

From 69022c73bcab30694cdda42df7e59348778cd90c Mon Sep 17 00:00:00 2001
From: matt <matt@claritum.com>
Date: Thu, 13 Nov 2025 09:25:00 +0000
Subject: [PATCH 3/4] Skip test if pcntl not available, remove require-dev

---
 composer.json                                  | 3 ---
 tests/end-to-end/cli/child-process-output.phpt | 5 +++++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/composer.json b/composer.json
index ab3171616d..4d443951aa 100644
--- a/composer.json
+++ b/composer.json
@@ -48,9 +48,6 @@
         "sebastian/version": "^6.0.0",
         "staabm/side-effects-detector": "^1.0.5"
     },
-    "require-dev": {
-        "ext-pcntl": "*"
-    },
     "config": {
         "platform": {
             "php": "8.3.0"
diff --git a/tests/end-to-end/cli/child-process-output.phpt b/tests/end-to-end/cli/child-process-output.phpt
index d85e4a1c44..ca0edad990 100644
--- a/tests/end-to-end/cli/child-process-output.phpt
+++ b/tests/end-to-end/cli/child-process-output.phpt
@@ -1,5 +1,10 @@
 --TEST--
 ShutdownHandler does not output when child process exits
+--SKIPIF--
+<?php declare(strict_types=1);
+if (!extension_loaded('pcntl')) {
+    print 'skip: Extension pcntl must be loaded.';
+}
 --FILE--
 <?php declare(strict_types=1);
 $_SERVER['argv'][] = '--do-not-cache-result';

From cbccb67997abeb151a3202c72482e65a44fbf5a3 Mon Sep 17 00:00:00 2001
From: matt <matt@claritum.com>
Date: Thu, 13 Nov 2025 09:27:00 +0000
Subject: [PATCH 4/4] Remove unnecessary filter

---
 tests/end-to-end/cli/child-process-output.phpt | 2 --
 1 file changed, 2 deletions(-)

diff --git a/tests/end-to-end/cli/child-process-output.phpt b/tests/end-to-end/cli/child-process-output.phpt
index ca0edad990..3624916670 100644
--- a/tests/end-to-end/cli/child-process-output.phpt
+++ b/tests/end-to-end/cli/child-process-output.phpt
@@ -9,8 +9,6 @@ if (!extension_loaded('pcntl')) {
 <?php declare(strict_types=1);
 $_SERVER['argv'][] = '--do-not-cache-result';
 $_SERVER['argv'][] = '--no-configuration';
-$_SERVER['argv'][] = '--filter';
-$_SERVER['argv'][] = 'testChildProcessOutput';
 $_SERVER['argv'][] = __DIR__ . '/../_files/ChildProcessTest.php';
 
 require __DIR__ . '/../../bootstrap.php';