--- /dev/null
+<?php
+
+namespace Drupal\Tests\block_content\Kernel\Plugin\migrate\source\d6;
+
+use Drupal\Tests\migrate\Kernel\MigrateSqlSourceTestBase;
+
+/**
+ * Tests D6 block boxes source plugin.
+ *
+ * @covers \Drupal\block_content\Plugin\migrate\source\d6\Box
+ * @group block_content
+ */
+class BoxTest extends MigrateSqlSourceTestBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public static $modules = ['block_content', 'migrate_drupal'];
+
+ /**
+ * {@inheritdoc}
+ */
+ public function providerSource() {
+ $tests = [];
+
+ $tests[0]['source_data']['boxes'] = [
+ [
+ 'bid' => 1,
+ 'body' => '<p>I made some custom content.</p>',
+ 'info' => 'Static Block',
+ 'format' => 1,
+ ],
+ [
+ 'bid' => 2,
+ 'body' => '<p>I made some more custom content.</p>',
+ 'info' => 'Test Content',
+ 'format' => 1,
+ ],
+ ];
+ // The expected results are identical to the source data.
+ $tests[0]['expected_data'] = $tests[0]['source_data']['boxes'];
+
+ return $tests;
+ }
+
+}