Issue #3438034 by tannguyenhn, adwivedi008, alex.skrypnyk, alexpott: Fix Composer Scaffold plugin event listeners

(cherry picked from commit f35f0419c7)

composer/Plugin/Scaffold/Handler.php

@@ -3,7 +3,6 @@
 namespace Drupal\Composer\Plugin\Scaffold;
 
 use Composer\Composer;
-use Composer\EventDispatcher\EventDispatcher;
 use Composer\Installer\PackageEvent;
 use Composer\IO\IOInterface;
 use Composer\Package\PackageInterface;
@@ -143,7 +142,7 @@ class Handler {
     }
 
     // Call any pre-scaffold scripts that may be defined.
-    $dispatcher = new EventDispatcher($this->composer, $this->io);
+    $dispatcher = $this->composer->getEventDispatcher();
     $dispatcher->dispatch(self::PRE_DRUPAL_SCAFFOLD_CMD);
 
     // Fetch the list of file mappings from each allowed package and normalize

core/tests/Drupal/Tests/Composer/Plugin/Scaffold/Functional/ComposerHookTest.php

@@ -148,4 +148,15 @@ class ComposerHookTest extends BuildTestBase {
     $this->assertStringNotContainsString('- Copy [web-root]/update.php from assets/update.php', $stdout);
   }
 
+  /**
+   * Tests to see if scaffold events are dispatched and picked up by the plugin.
+   */
+  public function testScaffoldEvents(): void {
+    $topLevelProjectDir = 'scaffold-events-fixture';
+    $sut = $this->fixturesDir . '/' . $topLevelProjectDir;
+    $output = $this->mustExec("composer install --no-ansi", $sut);
+    $this->assertStringContainsString('Hello preDrupalScaffoldCmd', $output);
+    $this->assertStringContainsString('Hello postDrupalScaffoldCmd', $output);
+  }
+
 }

core/tests/Drupal/Tests/Composer/Plugin/Scaffold/fixtures/composer-plugin-implements-scaffold-events/composer.json

@@ -0,0 +1,17 @@
+{
+  "name": "fixtures/composer-plugin-implements-scaffold-events",
+  "type": "composer-plugin",
+  "require": {
+    "php": ">=8.2",
+    "composer-plugin-api": "^2",
+    "drupal/core-composer-scaffold": "*"
+  },
+  "autoload": {
+    "psr-4": {
+      "Drupal\\Tests\\fixture\\Composer\\Plugin\\": "src"
+    }
+  },
+  "extra": {
+    "class": "Drupal\\Tests\\fixture\\Composer\\Plugin\\ComposerPluginImplementsScaffoldEvents"
+  }
+}

core/tests/Drupal/Tests/Composer/Plugin/Scaffold/fixtures/composer-plugin-implements-scaffold-events/src/ComposerPluginImplementsScaffoldEvents.php

@@ -0,0 +1,64 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\Tests\fixture\Composer\Plugin;
+
+use Composer\EventDispatcher\Event;
+use Composer\EventDispatcher\EventSubscriberInterface;
+use Composer\Plugin\PluginInterface;
+use Composer\Composer;
+use Composer\IO\IOInterface;
+use Drupal\Composer\Plugin\Scaffold\Handler;
+
+/**
+ * A fixture composer plugin implement Drupal scaffold events.
+ */
+class ComposerPluginImplementsScaffoldEvents implements PluginInterface, EventSubscriberInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [
+      Handler::PRE_DRUPAL_SCAFFOLD_CMD => 'preDrupalScaffoldCmd',
+      Handler::POST_DRUPAL_SCAFFOLD_CMD => 'postDrupalScaffoldCmd',
+    ];
+  }
+
+  /**
+   * Implements pre Drupal scaffold cmd.
+   */
+  public static function preDrupalScaffoldCmd(Event $event): void {
+    print 'Hello preDrupalScaffoldCmd' . PHP_EOL;
+  }
+
+  /**
+   * Implements post Drupal scaffold cmd.
+   */
+  public static function postDrupalScaffoldCmd(Event $event): void {
+    print 'Hello postDrupalScaffoldCmd' . PHP_EOL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function activate(Composer $composer, IOInterface $io) {
+
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deactivate(Composer $composer, IOInterface $io) {
+
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function uninstall(Composer $composer, IOInterface $io) {
+
+  }
+
+}

core/tests/Drupal/Tests/Composer/Plugin/Scaffold/fixtures/scaffold-events-fixture/composer.json.tmpl

@@ -0,0 +1,44 @@
+{
+  "name": "fixtures/drupal-drupal",
+  "type": "project",
+  "minimum-stability": "dev",
+  "prefer-stable": true,
+  "repositories": {
+    "packagist.org": false,
+    "composer-scaffold": {
+      "type": "path",
+      "url": "__PROJECT_ROOT__",
+      "options": {
+        "symlink": true
+      }
+    },
+    "fixtures/composer-plugin-implements-scaffold-events": {
+      "type": "path",
+      "url": "../composer-plugin-implements-scaffold-events",
+      "options": {
+        "symlink": true
+      }
+    }
+  },
+  "require": {
+    "drupal/core-composer-scaffold": "*",
+    "fixtures/composer-plugin-implements-scaffold-events": "*"
+  },
+  "extra": {
+    "drupal-scaffold": {
+      "allowed-packages": [
+        "fixtures/composer-plugin-implements-scaffold-events"
+      ],
+      "locations": {
+        "web-root": "./"
+      },
+      "symlink": __SYMLINK__
+    }
+  },
+  "config": {
+     "allow-plugins": {
+       "drupal/core-composer-scaffold": true,
+       "fixtures/composer-plugin-implements-scaffold-events": true
+     }
+  }
+}