fix: #3607866 Scaffold plugin does not always create autoload_runtime.php when upgrading to 11.4

   */

  public function postCmd(Event $event) {

    $this->handler()->scaffold();

    $this->ensureAutoloadRuntimeFile();

  }

  /**

   * Generates autoload_runtime.php when Handler::scaffold() did not.

   *

   * When this plugin package is itself updated during a Composer command,

   * the Handler class may already have been loaded from the previous version

   * of the plugin (via postPackage()) before the plugin files were replaced

   * on disk. PHP keeps the loaded class for the rest of the process, so

   * Handler::scaffold() then runs the old code, which does not generate the

   * autoload_runtime.php file (introduced in Drupal 11.4.0).

   *

   * Composer reloads this Plugin class from the new plugin code after the

   * plugin package is updated. It must only use other classes of this plugin

   * through APIs that exist in every version of the plugin that can be updated

   * from, because those classes may still be loaded from a previous version.

   *

   * @todo Remove after upgrades from Drupal 11.3 are no longer supported.

   *

   * @see \Composer\Plugin\PluginManager::registerPackage()

   * @see https://www.drupal.org/project/drupal/issues/3607866

   */

  protected function ensureAutoloadRuntimeFile(): void {

    $manage_options = new ManageOptions($this->composer);

    $allowed_packages = (new AllowedPackages($this->composer, $this->io, $manage_options))->getAllowedPackages();

    if (empty($allowed_packages)) {

      return;

    }

    $web_root = $manage_options->getOptions()->getLocation('web-root');

    if (file_exists($web_root . '/autoload_runtime.php')) {

      return;

    }

    $vendor_dir = $this->composer->getConfig()->get('vendor-dir');

    $vendor_path = (new Filesystem())->normalizePath(realpath($vendor_dir));

    $package_name = $this->composer->getPackage()->getName();

    $result = GenerateAutoloadRuntimeReferenceFile::generateAutoloadRuntime($this->io, $package_name, $web_root, $vendor_path);

    $git_ignore_manager = new ManageGitIgnore($this->io, getcwd());

    $git_ignore_manager->manageIgnored([$result], $manage_options->getOptions());

  }

  /**

    $this->fixtures->createIsolatedComposerCacheDir();

  }

  /**

   * {@inheritdoc}

   */

  protected function tearDown(): void {

    $this->fixtures->tearDown();

  }

  /**

   * Tests upgrading the Composer Scaffold plugin.

   */

    $this->assertFileExists("$sut/index.php");

  }

  /**

   * Tests upgrading the plugin when the Handler class is stale.

   *

   * @see \Drupal\Composer\Plugin\Scaffold\Plugin::ensureAutoloadRuntimeFile()

   */

  public function testUpgradeWithStaleHandler(): void {

    $this->fixturesDir = $this->fixtures->tmpDir($this->name());

    $pluginSource = $this->fixturesDir . '/composer-scaffold-plugin';

    $replacements = ['SYMLINK' => 'false', 'PROJECT_ROOT' => $pluginSource];

    $this->fixtures->cloneFixtureProjects($this->fixturesDir, $replacements);

    $sut = $this->fixturesDir . '/drupal-drupal';

    // The Scaffold plugin must be copied rather than symlinked into the

    // vendor directory, so that the installed plugin keeps the old code

    // after the plugin source is updated below.

    $composerJson = json_decode(file_get_contents("$sut/composer.json"), TRUE);

    $composerJson['repositories']['composer-scaffold']['options']['symlink'] = FALSE;

    file_put_contents("$sut/composer.json", json_encode($composerJson, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));

    // Create an "old" copy of the Scaffold plugin that behaves like the

    // plugin from before Drupal 11.4.0: it knows nothing about

    // autoload_runtime.php.

    $this->copyPluginVersion($pluginSource, '100.0.0', TRUE);

    $this->mustExec('composer install --no-ansi', $sut);

    $this->assertFileExists("$sut/autoload.php");

    $this->assertFileDoesNotExist("$sut/autoload_runtime.php");

    // Replace the plugin source with the current code, then require a

    // package containing a Composer plugin flagged with

    // 'plugin-modifies-downloads'. Composer will install that package before

    // the Scaffold plugin's update operation, so its post-package-install

    // event fires while the old Scaffold plugin code is still installed,

    // pinning the old Handler class for the remainder of the process.

    $this->copyPluginVersion($pluginSource, '100.0.1', FALSE);

    $composerJson['repositories']['downloads-modifier'] = [

      'type' => 'path',

      'url' => '../composer-plugin-downloads-modifier',

    ];

    $composerJson['require']['fixtures/composer-plugin-downloads-modifier'] = '*';

    $composerJson['config']['allow-plugins']['fixtures/composer-plugin-downloads-modifier'] = TRUE;

    file_put_contents("$sut/composer.json", json_encode($composerJson, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));

    $stdout = $this->mustExec('composer update --no-ansi --no-interaction 2>&1', $sut);

    // Verify that this test executed the stale Handler class: the

    // downloads-modifier plugin must have been installed before the Scaffold

    // plugin was updated, and the marker written by the stale Handler code

    // must appear in the output.

    $installPos = strpos($stdout, 'Installing fixtures/composer-plugin-downloads-modifier');

    $upgradePos = strpos($stdout, 'Upgrading drupal/core-composer-scaffold (100.0.0 => 100.0.1):');

    $this->assertNotFalse($installPos, $stdout);

    $this->assertNotFalse($upgradePos, $stdout);

    $this->assertLessThan($upgradePos, $installPos, $stdout);

    $this->assertStringContainsString('SCAFFOLD_TEST_STALE_HANDLER', $stdout);

    // Even though the stale Handler did not generate autoload_runtime.php,

    // the refreshed Plugin class must have generated it.

    $this->assertFileExists("$sut/autoload_runtime.php");

    $this->assertStringContainsString("require __DIR__ . '/vendor/autoload_runtime.php'", file_get_contents("$sut/autoload_runtime.php"));

  }

  /**

   * Copies the Scaffold plugin source to a target directory with a version.

   *

   * @param string $target

   *   Directory to place the plugin copy in.

   * @param string $version

   *   Version to set in the composer.json of the copy, so that the path

   *   repository provides an update when the version is bumped.

   * @param bool $stale

   *   When TRUE, remove all knowledge of autoload_runtime.php from the copy

   *   to simulate the plugin from before Drupal 11.4.0. A marker is written

   *   to output by the modified Handler so that tests can verify that the

   *   stale Handler code ran.

   */

  protected function copyPluginVersion(string $target, string $version, bool $stale): void {

    $filesystem = new Filesystem();

    $filesystem->remove($target);

    $filesystem->copy($this->fixtures->projectRoot(), $target);

    $composerJson = json_decode(file_get_contents("$target/composer.json"), TRUE);

    $composerJson['version'] = $version;

    file_put_contents("$target/composer.json", json_encode($composerJson, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));

    if ($stale) {

      $generateRuntime = <<<'PHP'

    // The same is done for the autoload_runtime file that loads the Symfony

    // runtime.

    if (!GenerateAutoloadRuntimeReferenceFile::autoloadRuntimeFileCommitted($this->io, $this->rootPackageName(), $web_root)) {

      $scaffold_results[] = GenerateAutoloadRuntimeReferenceFile::generateAutoloadRuntime($this->io, $this->rootPackageName(), $web_root, $this->getVendorPath());

    }

PHP;

      $this->replaceCodeInFile("$target/Handler.php", $generateRuntime, "    \$this->io->write('SCAFFOLD_TEST_STALE_HANDLER');");

      $this->replaceCodeInFile("$target/Plugin.php", "    \$this->ensureAutoloadRuntimeFile();\n", '');

      unlink("$target/GenerateAutoloadRuntimeReferenceFile.php");

    }

  }

  /**

   * Replaces a code fragment in a file.

   *

   * @param string $path

   *   Path of the file to modify.

   * @param string $search

   *   The code fragment to replace.

   * @param string $replace

   *   The replacement code fragment.

   */

  protected function replaceCodeInFile(string $path, string $search, string $replace): void {

    $contents = file_get_contents($path);

    $this->assertStringContainsString($search, $contents, "Expected code not found in $path; update this test to match the current code.");

    file_put_contents($path, str_replace($search, $replace, $contents));

  }

  /**

   * Copy the provided source directory and create a temporary git repository.

   *

{

  "name": "fixtures/composer-plugin-downloads-modifier",

  "type": "composer-plugin",

  "require": {

    "composer-plugin-api": "^2"

  },

  "autoload": {

    "psr-4": {

      "Drupal\\Tests\\fixture\\Composer\\Plugin\\DownloadsModifier\\": "src"

    }

  },

  "extra": {

    "class": "Drupal\\Tests\\fixture\\Composer\\Plugin\\DownloadsModifier\\DownloadsModifierPlugin",

    "plugin-modifies-downloads": true

  }

}

<?php

declare(strict_types=1);

namespace Drupal\Tests\fixture\Composer\Plugin\DownloadsModifier;

use Composer\Composer;

use Composer\IO\IOInterface;

use Composer\Plugin\PluginInterface;

/**

 * A do-nothing Composer plugin flagged with 'plugin-modifies-downloads'.

 *

 * Composer moves the install operation of such a plugin in front of all

 * other plugin operations. Tests use this to force a post-package-install

 * event to fire before the Scaffold plugin's own update operation executes.

 *

 * @see \Composer\DependencyResolver\Transaction::movePluginsToFront()

 */

class DownloadsModifierPlugin implements PluginInterface {

  /**

   * {@inheritdoc}

   */

  public function activate(Composer $composer, IOInterface $io): void {

  }

  /**

   * {@inheritdoc}

   */

  public function deactivate(Composer $composer, IOInterface $io): void {

  }

  /**

   * {@inheritdoc}

   */

  public function uninstall(Composer $composer, IOInterface $io): void {

  }

}