diff --git a/core/modules/comment/src/Tests/Update/CommentUpdateTest.php b/core/modules/comment/src/Tests/Update/CommentUpdateTest.php
index 3db9c4a67b..bf4baff3ca 100644
--- a/core/modules/comment/src/Tests/Update/CommentUpdateTest.php
+++ b/core/modules/comment/src/Tests/Update/CommentUpdateTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\comment\Tests\Update;
 
+use Drupal\Core\Database\Database;
 use Drupal\system\Tests\Update\UpdatePathTestBase;
 
 /**
@@ -71,4 +72,29 @@ public function testPublishedEntityKey() {
     $this->assertTrue(\Drupal::database()->schema()->indexExists('comment_field_data', 'comment__status_comment_type'));
   }
 
+  /**
+   * Tests whether the 'entity_type' column is required.
+   *
+   * @see comment_update_8204()
+   */
+  public function testCommentEntityTypeRequired() {
+    $this->assertEqual(2, Database::getConnection()->query('SELECT count(*) FROM {comment_field_data}')->fetchField());
+    if (Database::getConnection()->driver() === 'mysql') {
+      $table_description = \Drupal::database()
+        ->query('DESCRIBE comment_field_data')
+        ->fetchAllAssoc('Field');
+      $this->assertEqual($table_description['entity_type']->Null, 'YES');
+    }
+
+    $this->runUpdates();
+
+    $this->assertEqual(2, Database::getConnection()->query('SELECT count(*) FROM {comment_field_data}')->fetchField());
+    if (Database::getConnection()->driver() === 'mysql') {
+      $table_description = \Drupal::database()
+        ->query('DESCRIBE comment_field_data')
+        ->fetchAllAssoc('Field');
+      $this->assertEqual($table_description['entity_type']->Null, 'NO');
+    }
+  }
+
 }