Issue #2917883 by quietone, TR, Jo Fitzgerald, masipila, phenaproxima: Rename 'migration_templates' directories in core modules to 'migrations'

core/modules/migrate/migrate.api.php

@@ -38,9 +38,8 @@ use Drupal\migrate\Row;
  *
  * @section sec_migrations Migration plugins
  * Migration plugin definitions are stored in a module's 'migrations' directory.
- * For backwards compatibility we also scan the 'migration_templates' directory.
  * Examples of migration plugin definitions can be found in
- * 'core/modules/action/migration_templates'. The plugin class is
+ * 'core/modules/action/migrations'. The plugin class is
  * \Drupal\migrate\Plugin\Migration, with interface
  * \Drupal\migrate\Plugin\MigrationInterface. Migration plugins are managed by
  * the \Drupal\migrate\Plugin\MigrationPluginManager class. Migration plugins

core/modules/migrate/src/Plugin/MigrationPluginManager.php

@@ -60,11 +60,22 @@ class MigrationPluginManager extends DefaultPluginManager implements MigrationPl
   }
 
   /**
-   * {@inheritdoc}
+   * Gets the plugin discovery.
+   *
+   * This method overrides DefaultPluginManager::getDiscovery() in order to
+   * search for migration configurations in the MODULENAME/migrations and
+   * MODULENAME/migration_templates directories. Throws a deprecation notice if
+   * the MODULENAME/migration_templates directory exists.
    */
   protected function getDiscovery() {
     if (!isset($this->discovery)) {
       $directories = array_map(function ($directory) {
+        // Check for use of the @deprecated /migration_templates directory.
+        // @todo Remove use of /migration_templates in Drupal 9.0.0.
+        if (is_dir($directory . '/migration_templates')) {
+          @trigger_error('Use of the /migration_templates directory to store migration configuration files is deprecated in Drupal 8.1.0 and will be removed before Drupal 9.0.0. See https://www.drupal.org/node/2920988.', E_USER_DEPRECATED);
+        }
+        // But still accept configurations found in /migration_templates.
         return [$directory . '/migration_templates', $directory . '/migrations'];
       }, $this->moduleHandler->getModuleDirectories());
 

core/modules/migrate/tests/modules/migration_directory_test/migration_directory_test.info.yml

@@ -0,0 +1,7 @@
+name: 'Migration directory test'
+type: module
+package: Testing
+version: VERSION
+core: 8.x
+dependencies:
+  - migrate

core/modules/migrate/tests/modules/migration_directory_test/migration_templates/migration_templates_test.yml

@@ -0,0 +1,8 @@
+id: migration_templates_test
+label: Migration templates test
+source:
+  plugin: embedded_data
+process:
+  id: id
+destination:
+  plugin: null

core/modules/migrate/tests/src/Kernel/Plugin/MigrationDirectoryTest.php

@@ -0,0 +1,29 @@
+<?php
+
+namespace Drupal\Tests\migrate\Kernel\Plugin;
+
+use Drupal\Tests\migrate_drupal\Kernel\MigrateDrupalTestBase;
+
+/**
+ * Tests that migrations exist in the migration_templates directory.
+ *
+ * @group migrate
+ */
+class MigrationDirectoryTest extends MigrateDrupalTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['migration_directory_test'];
+
+  /**
+   * Tests that migrations in the migration_templates directory are created.
+   */
+  public function testMigrationDirectory() {
+    /** @var \Drupal\migrate\Plugin\MigrationPluginManager $plugin_manager */
+    $plugin_manager = $this->container->get('plugin.manager.migration');
+    // Tests that a migration in directory 'migration_templates' is discovered.
+    $this->assertTrue($plugin_manager->hasDefinition('migration_templates_test'));
+  }
+
+}