diff --git a/core/modules/dblog/src/Tests/ConnectionFailureTest.php b/core/modules/dblog/src/Tests/ConnectionFailureTest.php
new file mode 100644
index 0000000..ff6de07
--- /dev/null
+++ b/core/modules/dblog/src/Tests/ConnectionFailureTest.php
@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * @file
+ * Definition of \Drupal\dblog\Tests\ConnectionFailureTest.
+ */
+
+namespace Drupal\dblog\Tests;
+
+use Drupal\Core\Database\Database;
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests loging of connection failures.
+ *
+ * @group dblog
+ */
+class ConnectionFailureTest extends WebTestBase {
+
+  public static $modules = array('dblog');
+
+  /**
+   * Tests loging of connection failures.
+   */
+  function testConnectionFailureLogging() {
+    $logger = \Drupal::service('logger.factory');
+
+    // MySQL erros like "1153 – Got a packet bigger than ‘max_allowed_packet’
+    // bytes" or "1100 - Table 'xyz' was not locked with LOCK TABLES" lead to a
+    // database connection unusable for further request. All further request
+    // will result in an "2006 - MySQL server had gone away" error. As a
+    // consequence it's impossible to use this connection to log the causing
+    // initial error itself. Using Database::closeConnection() we simulate such
+    // a corrupted connection. In this case dblog has to establish a different
+    // connection by itself to be able to write the log entry.
+    Database::closeConnection();
+
+    // Create a log entry.
+    $logger->get('php')->error('testConnectionFailureLogging');
+
+    // Re-establish the default database connection.
+    Database::getConnection();
+
+    $wid = db_query("SELECT MAX(wid) FROM {watchdog} WHERE message = 'testConnectionFailureLogging'")->fetchField();
+    $this->assertTrue($wid, 'Watchdog entry has been stored in database.');
+  }
+
+}