PHPT: Trigger runner warning on parse-error in SKIPIF

Author: staabm

src/Runner/Phpt/TestCase.php

@@ -350,6 +350,15 @@ private function shouldTestBeSkipped(array $sections, array $settings): bool
             $output = $this->runCodeInLocalSandbox($skipIfCode);
         }
 
+        if (str_contains($output, 'Parse error:')) {
+            EventFacade::emitter()->testRunnerTriggeredPhpunitWarning(
+                sprintf(
+                    'SKIPIF section triggered a parse error: %s',
+                    $output,
+                ),
+            );
+        }
+
         if (str_contains($output, 'Fatal error:')) {
             EventFacade::emitter()->testRunnerTriggeredPhpunitWarning(
                 sprintf(

tests/end-to-end/_files/phpt-skipif-parse-error.phpt

@@ -0,0 +1,11 @@
+--TEST--
+https://github.com/sebastianbergmann/phpunit/issues/5991
+--SKIPIF--
+<?php
+if (rand(0,1)) // intentional PHP Parse error (missing opening curly brace)
+}
+--FILE--
+<?php declare(strict_types=1);
+echo 'hello world';
+--EXPECTF--
+hello world

tests/end-to-end/regression/5991.phpt

@@ -0,0 +1,28 @@
+--TEST--
+https://github.com/sebastianbergmann/phpunit/issues/5991
+--FILE--
+<?php declare(strict_types=1);
+$_SERVER['argv'][] = '--do-not-cache-result';
+$_SERVER['argv'][] = '--no-configuration';
+$_SERVER['argv'][] = __DIR__ . '/../_files/phpt-skipif-parse-error.phpt';
+
+require_once __DIR__ . '/../../bootstrap.php';
+
+(new PHPUnit\TextUI\Application)->run($_SERVER['argv']);
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+Runtime: %s
+
+.                                                                   1 / 1 (100%)
+
+Time: %s, Memory: %s
+
+There was 1 PHPUnit test runner warning:
+
+1) SKIPIF section triggered a parse error: 
+Parse error: Unmatched '}' in Standard input code on line 3
+
+
+OK, but there were issues!
+Tests: 1, Assertions: 1, PHPUnit Warnings: 1.