Emit warning when OPCache is enabled while collecting coverage

.github/workflows/ci.yaml

@@ -196,13 +196,73 @@ jobs:
       - name: Run tests with PHPUnit
         run: php ./phpunit --testsuite end-to-end --order-by depends,random
 
+  end-to-end-tests-with-coverage-driver:
+    name: End-to-End Tests with Coverage Driver
+
+    needs:
+      - unit-tests
+
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 5
+
+    env:
+      PHP_EXTENSIONS: none, ctype, curl, dom, json, libxml, mbstring, openssl, pdo, phar, tokenizer, xml, xmlwriter
+      PHP_INI_VALUES: zend.assertions=1, error_reporting=-1, log_errors_max_len=0, display_errors=On
+
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - windows-latest
+
+        php-version:
+          - "8.3"
+          - "8.4"
+          - "8.5"
+
+    steps:
+      - name: Configure Git to avoid issues with line endings
+        if: matrix.os == 'windows-latest'
+        run: git config --global core.autocrlf false
+
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
+
+      - name: Use local branch
+        shell: bash
+        run: |
+          BRANCH=$([ "${{ github.event_name }}" == "pull_request" ] && echo "${{ github.head_ref }}" || echo "${{ github.ref_name }}")
+          git branch -D $BRANCH 2>/dev/null || true
+          git branch $BRANCH HEAD
+          git checkout $BRANCH
+
+      - name: Install PHP with extensions
+        uses: shivammathur/setup-php@v2
+        with:
+          coverage: xdebug
+          php-version: ${{ matrix.php-version }}
+          extensions: ${{ env.PHP_EXTENSIONS }}
+          ini-values: ${{ env.PHP_INI_VALUES }}
+          tools: none
+
+      - name: Install dependencies with Composer
+        run: php ./tools/composer install --no-ansi --no-interaction --no-progress
+
+      - name: Run tests with PHPUnit
+        run: php ./phpunit --testsuite end-to-end-with-coverage-driver --order-by depends,random
+
   code-coverage:
     name: Code Coverage
 
     if: github.event_name != 'schedule'
 
     needs:
       - end-to-end-tests
+      - end-to-end-tests-with-coverage-driver
 
     runs-on: ubuntu-latest
     timeout-minutes: 10

phpunit.xml

@@ -47,6 +47,10 @@
             <exclude>tests/end-to-end/self-direct-indirect/_files</exclude>
             <exclude>tests/end-to-end/testdox/_files</exclude>
         </testsuite>
+
+        <testsuite name="end-to-end-with-coverage-driver">
+            <directory suffix=".phpt">tests/end-to-end-with-coverage-driver/warn-when-opcache-enabled</directory>
+        </testsuite>
     </testsuites>
 
     <source ignoreIndirectDeprecations="true" restrictNotices="true" restrictWarnings="true">

src/Runner/CodeCoverage.php

@@ -40,6 +40,7 @@
 use SebastianBergmann\CodeCoverage\Test\TestSize\TestSize;
 use SebastianBergmann\CodeCoverage\Test\TestStatus\TestStatus;
 use SebastianBergmann\Comparator\Comparator;
+use SebastianBergmann\Environment\Runtime;
 use SebastianBergmann\Timer\NoActiveTimerException;
 use SebastianBergmann\Timer\Timer;
 
@@ -124,6 +125,14 @@ public function init(Configuration $configuration, CodeCoverageFilterRegistry $c
             $this->codeCoverage()->excludeUncoveredFiles();
         }
 
+        $runtime = new Runtime;
+
+        if ($runtime->isOpcacheActive()) {
+            EventFacade::emitter()->testRunnerTriggeredPhpunitWarning(
+                'Code coverage might produce unreliable results when OPCache is enabled',
+            );
+        }
+
         if ($codeCoverageFilterRegistry->get()->isEmpty()) {
             if (!$codeCoverageFilterRegistry->configured()) {
                 EventFacade::emitter()->testRunnerTriggeredPhpunitWarning(

tests/end-to-end-with-coverage-driver/warn-when-opcache-enabled/src/Greeter.php

@@ -0,0 +1,18 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\CoverageWithOpcacheEnabled;
+
+final class Greeter
+{
+    public function greet(): string
+    {
+        return 'Hello world!';
+    }
+}

tests/end-to-end-with-coverage-driver/warn-when-opcache-enabled/src/autoload.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types=1);
+
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+require_once __DIR__ . '/Greeter.php';

tests/end-to-end-with-coverage-driver/warn-when-opcache-enabled/tests/GreeterTest.php

@@ -0,0 +1,25 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\CoverageWithOpcacheEnabled;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\RunInSeparateProcess;
+use PHPUnit\Framework\Attributes\Ticket;
+use PHPUnit\Framework\TestCase;
+
+#[CoversClass(Greeter::class)]
+final class GreeterTest extends TestCase
+{
+    public function testGreets(): void
+    {
+        $this->assertSame('Hello world!', (new Greeter)->greet());
+    }
+
+}

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

@@ -0,0 +1,42 @@
+--TEST--
+https://github.com/sebastianbergmann/php-code-coverage/issues/1022
+--INI--
+opcache.enable_cli=1
+opcache.jit=disable
+--ENV--
+XDEBUG_MODE=coverage
+--SKIPIF--
+<?php declare(strict_types=1);
+require __DIR__ . '/../../_files/skip-if-requires-code-coverage-driver.php';
+
+if (!extension_loaded('Zend OPcache')) {
+    echo 'skip: opcache extension is not loaded';
+}
+--FILE--
+<?php declare(strict_types=1);
+$_SERVER['argv'][] = '--do-not-cache-result';
+$_SERVER['argv'][] = '--colors=never';
+$_SERVER['argv'][] = '--coverage-text';
+$_SERVER['argv'][] = '--bootstrap';
+$_SERVER['argv'][] = __DIR__.'/src/autoload.php';
+$_SERVER['argv'][] = '--coverage-filter';
+$_SERVER['argv'][] = __DIR__.'/src/';
+$_SERVER['argv'][] = __DIR__.'/tests/GreeterTest.php';
+
+require_once __DIR__ . '/../../bootstrap.php';
+
+(new PHPUnit\TextUI\Application)->run($_SERVER['argv']);
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+Runtime: %s
+Configuration: %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
+%A