only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/menu_link_content/tests/src/Kernel/Plugin/migrate/source/d6/I18nMenuLinkSourceTest.php
@@ -0,0 +1,175 @@
+<?php
+
+namespace Drupal\Tests\menu_link_content\Unit\Plugin\migrate\source\d6;
+
+use Drupal\Tests\migrate\Unit\MigrateSqlSourceTestCase;
+
+/**
+ * Tests i18n menu link source plugin.
+ *
+ * @group config_translation
+ */
+class I18nMenuLinkSourceTest extends MigrateSqlSourceTestCase {
+
+  const PLUGIN_CLASS = 'Drupal\menu_link_content\Plugin\migrate\source\d6\I18nMenuLink';
+
+  protected $migrationConfiguration = [
+    'id' => 'id',
+    'source' => [
+      'plugin' => 'test',
+    ],
+  ];
+
+  protected $menu_links = [
+    [
+      'menu_name' => 'menu-test-menu',
+      'mlid' => 138,
+      'plid' => 0,
+      'link_path' => 'admin',
+      'router_path' => 'admin',
+      'link_title' => 'Test 1',
+      'options' => ['attributes' => ['title' => 'Test menu link 1']],
+      'module' => 'menu',
+      'hidden' => 0,
+      'external' => 0,
+      'has_children' => 1,
+      'expanded' => 0,
+      'weight' => 15,
+      'depth' => 1,
+      'customized' => 1,
+      'p1' => '138',
+      'p2' => '0',
+      'p3' => '0',
+      'p4' => '0',
+      'p5' => '0',
+      'p6' => '0',
+      'p7' => '0',
+      'p8' => '0',
+      'p9' => '0',
+      'updated' => '0',
+      'description' => 'Test menu link 1',
+    ],
+    [
+      'menu_name' => 'menu-test-menu',
+      'mlid' => 139,
+      'plid' => 138,
+      'link_path' => 'admin/modules',
+      'router_path' => 'admin/modules',
+      'link_title' => 'Test 2',
+      'options' => ['attributes' => ['title' => 'Test menu link 2']],
+      'module' => 'menu',
+      'hidden' => 0,
+      'external' => 0,
+      'has_children' => 0,
+      'expanded' => 0,
+      'weight' => 12,
+      'depth' => 2,
+      'customized' => 1,
+      'p1' => '138',
+      'p2' => '139',
+      'p3' => '0',
+      'p4' => '0',
+      'p5' => '0',
+      'p6' => '0',
+      'p7' => '0',
+      'p8' => '0',
+      'p9' => '0',
+      'updated' => '0',
+      'description' => 'Test menu link 2',
+    ],
+  ];
+
+  protected $i18n_strings = [
+    [
+      'lid' => 1,
+      'objectid' => 139,
+      'type' => 'item',
+      'property' => 'title',
+      'objectindex' => 0,
+      'format' => 0,
+    ],
+    [
+      'lid' => 2,
+      'objectid' => 139,
+      'type' => 'item',
+      'property' => 'description',
+      'objectindex' => 0,
+      'format' => 0,
+    ],
+    [
+      'lid' => 3,
+      'objectid' => 138,
+      'type' => 'item',
+      'property' => 'description',
+      'objectindex' => 0,
+      'format' => 0,
+    ]
+  ];
+
+  protected $locales_target = [
+    [
+      'lid' => 1,
+      'language' => 'fr',
+      'translation' => 'fr - title translation',
+      'plid' => 0,
+      'plural' => 0,
+      'u18n_status' => 0,
+    ],
+    [
+      'lid' => 2,
+      'language' => 'fr',
+      'translation' => 'fr - description translation',
+      'plid' => 0,
+      'plural' => 0,
+      'u18n_status' => 0,
+    ],
+    [
+      'lid' => 3,
+      'language' => 'zu',
+      'translation' => 'zu - description translation',
+      'plid' => 0,
+      'plural' => 0,
+      'u18n_status' => 0,
+    ],
+  ];
+
+  protected $expectedResults = [
+    [
+      'mlid' => 138,
+      'link_path' => 'admin',
+      'options' => 'a:1:{s:10:"attributes";a:1:{s:5:"title";s:16:"Test menu link 1";}}',
+      'objectid' => 138,
+      'language' => 'zu',
+      'ltlid' => 3,
+      'title' => 'Test 1',
+      'description' => 'zu - description translation',
+
+    ],
+    [
+      'mlid' => 139,
+      'link_path' => 'admin/modules',
+      'options' => 'a:1:{s:10:"attributes";a:1:{s:5:"title";s:16:"Test menu link 2";}}',
+      'objectid' => 139,
+      'language' => 'fr',
+      'ltlid' => 1,
+      'title' => 'fr - title translation',
+      'description' => 'fr - description translation',
+    ],
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    $this->databaseContents['menu_links'] = $this->menu_links;
+    $this->databaseContents['i18n_strings'] = $this->i18n_strings;
+    $this->databaseContents['locales_target'] = $this->locales_target;
+
+    array_walk($this->databaseContents['menu_links'], function (&$row) {
+      $row['options'] = serialize($row['options']);
+    });
+
+    parent::setUp();
+  }
+
+}