Emit warning when OPCache is enabled while collecting coverage

Author: staabm

tests/end-to-end/code-coverage/warn-when-opcache-enabled.phpt

@@ -0,0 +1,43 @@
+--TEST--
+https://github.com/sebastianbergmann/php-code-coverage/issues/1022
+--INI--
+opcache.enable_cli=1
+--SKIPIF--
+<?php declare(strict_types=1);
+require __DIR__ . '/../../_files/skip-if-requires-code-coverage-driver.php';
+
+if (!function_exists('opcache_compile_file')) {
+    echo 'skip, opcache extension is not loaded';
+} elseif (ini_get('opcache.enable_cli') !== '1') {
+    echo 'skip, opcache not enabled for CLI';
+}
+--FILE--
+<?php declare(strict_types=1);
+$_SERVER['argv'][] = '--do-not-cache-result';
+$_SERVER['argv'][] = '--no-configuration';
+$_SERVER['argv'][] = '--bootstrap';
+$_SERVER['argv'][] = __DIR__ . '/ignore-class-using-attribute/src/CoveredClass.php';
+$_SERVER['argv'][] = '--coverage-filter';
+$_SERVER['argv'][] = __DIR__ . '/ignore-class-using-attribute/src';
+$_SERVER['argv'][] = '--coverage-text';
+$_SERVER['argv'][] = __DIR__ . '/ignore-class-using-attribute/tests';
+
+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 MB
+
+There was 1 PHPUnit test runner warning:
+
+1) Code coverage might produce unreliable results when OPCache is enabled.
+
+OK, but there were issues!
+Tests: 1, Assertions: 1, PHPUnit Warnings: 1.
+%A