Issue #2807939 by erozqba, svendecabooter: Convert System's Migrate source tests to new base class

core/modules/system/tests/src/Kernel/Plugin/migrate/source/MenuTest.php

+<?php
+
+namespace Drupal\Tests\system\Kernel\Plugin\migrate\source;
+
+use Drupal\Tests\migrate\Kernel\MigrateSqlSourceTestBase;
+
+/**
+ * Tests menu source plugin.
+ *
+ * @covers Drupal\system\Plugin\migrate\source\Menu
+ *
+ * @group system
+ */
+class MenuTest extends MigrateSqlSourceTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['system', 'migrate_drupal'];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function providerSource() {
+    $tests = [];
+
+    // The source data.
+    $tests[0]['source_data']['menu_custom'] = [
+      [
+        'menu_name' => 'menu-name-1',
+        'title' => 'menu custom value 1',
+        'description' => 'menu custom description value 1',
+      ],
+      [
+        'menu_name' => 'menu-name-2',
+        'title' => 'menu custom value 2',
+        'description' => 'menu custom description value 2',
+      ],
+    ];
+
+    // The expected results are identical to the source data.
+    $tests[0]['expected_data'] = $tests[0]['source_data']['menu_custom'];
+
+    return $tests;
+  }
+
+}

core/modules/system/tests/src/Unit/Plugin/migrate/source/MenuTest.php

-<?php
-
-namespace Drupal\Tests\system\Unit\Plugin\migrate\source;
-
-use Drupal\Tests\migrate\Unit\MigrateSqlSourceTestCase;
-
-/**
- * Tests menu source plugin.
- *
- * @group system
- */
-class MenuTest extends MigrateSqlSourceTestCase {
-
-  const PLUGIN_CLASS = 'Drupal\system\Plugin\migrate\source\Menu';
-
-  protected $migrationConfiguration = array(
-    'id' => 'test',
-    'source' => array(
-      'plugin' => 'menu',
-    ),
-  );
-
-  protected $expectedResults = array(
-    array(
-      'menu_name' => 'menu-name-1',
-      'title' => 'menu custom value 1',
-      'description' => 'menu custom description value 1',
-    ),
-    array(
-      'menu_name' => 'menu-name-2',
-      'title' => 'menu custom value 2',
-      'description' => 'menu custom description value 2',
-    ),
-  );
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp() {
-    $this->databaseContents['menu_custom'] = $this->expectedResults;
-    parent::setUp();
-  }
-
-}