Issue #2682705 by davidwbarratt, alexpott, vprocessor, miiimooo, milesw: Migrate process plugin does not save stubs to the idmap, leads to duplicates and broken references

core/modules/migrate/src/Plugin/migrate/process/Migration.php

@@ -11,6 +11,7 @@ use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\migrate\MigrateSkipProcessException;
 use Drupal\migrate\Plugin\MigratePluginManager;
 use Drupal\migrate\Plugin\MigrationPluginManagerInterface;
+use Drupal\migrate\Plugin\MigrateIdMapInterface;
 use Drupal\migrate\ProcessPluginBase;
 use Drupal\migrate\Plugin\MigrationInterface;
 use Drupal\migrate\MigrateExecutableInterface;
@@ -139,7 +140,11 @@ class Migration extends ProcessPluginBase implements ContainerFactoryPluginInter
         $destination_ids = $destination_plugin->import($stub_row);
       }
       catch (\Exception $e) {
-        $migrate_executable->saveMessage($e->getMessage());
+        $migration->getIdMap()->saveMessage($stub_row->getSourceIdValues(), $e->getMessage());
+      }
+
+      if ($destination_ids) {
+        $migration->getIdMap()->saveIdMapping($stub_row, $destination_ids, MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
       }
     }
     if ($destination_ids) {

core/modules/migrate/tests/src/Unit/process/MigrationTest.php

@@ -67,6 +67,7 @@ class MigrationTest extends MigrateProcessTestCase {
     $migration_plugin_manager->createInstances(['destination_migration'])
       ->willReturn(['destination_migration' => $destination_migration->reveal()]);
     $destination_id_map->lookupDestinationId([1])->willReturn(NULL);
+    $destination_id_map->saveIdMapping(Argument::any(), Argument::any(), MigrateIdMapInterface::STATUS_NEEDS_UPDATE)->willReturn(NULL);
 
     $configuration = [
       'no_stub' => FALSE,

core/modules/taxonomy/src/Tests/Migrate/MigrateTaxonomyTermStubTest.php

@@ -75,8 +75,11 @@ class MigrateTaxonomyTermStubTest extends MigrateDrupalTestBase {
 
     // We have a term referencing an unmigrated parent, forcing a stub to be
     // created.
-    $term_executable = new MigrateExecutable($this->getMigration('taxonomy_term_stub_test'), $this);
+    $migration = $this->getMigration('taxonomy_term_stub_test');
+    $term_executable = new MigrateExecutable($migration, $this);
     $term_executable->import();
+    $this->assertTrue($migration->getIdMap()->getRowBySource(['2']), 'Stub row exists in the ID map table');
+
     // Load the referenced term, which should exist as a stub.
     /** @var \Drupal\Core\Entity\ContentEntityBase $stub_entity */
     $stub_entity = Term::load(2);