diff --git a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
index 9b6f0e2..e5d6659 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
@@ -19,6 +19,13 @@
 class SqlContentEntityStorageSchemaTest extends UnitTestCase {
 
   /**
+   * The mocked DB schema handler.
+   *
+   * @var \Drupal\Core\Database\Schema|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $dbSchemaHandler;
+
+  /**
    * The mocked entity manager used in this test.
    *
    * @var \Drupal\Core\Entity\EntityManagerInterface|\PHPUnit_Framework_MockObject_MockObject
@@ -1298,7 +1305,7 @@ protected function setUpStorageSchema(array $expected = array()) {
       ->with($this->entityType->id())
       ->will($this->returnValue($this->storageDefinitions));
 
-    $db_schema_handler = $this->getMockBuilder('Drupal\Core\Database\Schema')
+    $this->dbSchemaHandler = $this->getMockBuilder('Drupal\Core\Database\Schema')
       ->disableOriginalConstructor()
       ->getMock();
 
@@ -1307,7 +1314,7 @@ protected function setUpStorageSchema(array $expected = array()) {
       $expected_table_names = array_keys($expected);
       $expected_table_schemas = array_values($expected);
 
-      $db_schema_handler->expects($this->any())
+      $this->dbSchemaHandler->expects($this->any())
         ->method('createTable')
         ->with(
           $this->callback(function($table_name) use (&$invocation_count, $expected_table_names) {
@@ -1327,17 +1334,21 @@ protected function setUpStorageSchema(array $expected = array()) {
       ->getMock();
     $connection->expects($this->any())
       ->method('schema')
-      ->will($this->returnValue($db_schema_handler));
+      ->will($this->returnValue($this->dbSchemaHandler));
 
     $key_value = $this->getMock('Drupal\Core\KeyValueStore\KeyValueStoreInterface');
     $this->storageSchema = $this->getMockBuilder('Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema')
       ->setConstructorArgs(array($this->entityManager, $this->entityType, $this->storage, $connection))
-      ->setMethods(array('installedStorageSchema', 'loadEntitySchemaData', 'hasSharedTableNameChanges'))
+      ->setMethods(array('installedStorageSchema', 'loadEntitySchemaData', 'hasSharedTableNameChanges', 'isTableEmpty'))
       ->getMock();
     $this->storageSchema
       ->expects($this->any())
       ->method('installedStorageSchema')
       ->will($this->returnValue($key_value));
+    $this->storageSchema
+      ->expects($this->any())
+      ->method('isTableEmpty')
+      ->willReturn(FALSE);
   }
 
   /**
@@ -1380,4 +1391,76 @@ public function setUpStorageDefinition($field_name, array $schema) {
     }
   }
 
+  /**
+   * ::onEntityTypeUpdate
+   */
+  public function testonEntityTypeUpdateWithNewIndex() {
+    $entity_type_id = 'entity_test';
+    $this->entityType = $original_entity_type = new ContentEntityType(array(
+      'id' => 'entity_test',
+      'entity_keys' => array('id' => 'id'),
+    ));
+
+    // Add a field with a really long index.
+    $this->setUpStorageDefinition('long_index_name', array(
+      'columns' => array(
+        'long_index_name' => array(
+          'type' => 'int',
+        ),
+      ),
+      'indexes' => array(
+        'long_index_name_really_long_long_name' => array(array('long_index_name', 10)),
+      ),
+    ));
+
+    $expected = array(
+      'entity_test' => array(
+        'description' => 'The base table for entity_test entities.',
+        'fields' => array(
+          'id' => array(
+            'type' => 'serial',
+            'not null' => TRUE,
+          ),
+          'long_index_name' => array(
+            'type' => 'int',
+            'not null' => FALSE,
+          ),
+        ),
+        'indexes' => array(
+          'entity_test__b588603cb9' => array(
+            array('long_index_name', 10),
+          ),
+        ),
+      ),
+    );
+
+    $this->setUpStorageSchema($expected);
+
+    $table_mapping = new DefaultTableMapping($this->entityType, $this->storageDefinitions);
+    $table_mapping->setFieldNames('entity_test', array_keys($this->storageDefinitions));
+    $table_mapping->setExtraColumns('entity_test', array('default_langcode'));
+
+    $this->storage->expects($this->any())
+      ->method('getTableMapping')
+      ->will($this->returnValue($table_mapping));
+
+    $this->storageSchema->expects($this->any())
+      ->method('loadEntitySchemaData')
+      ->willReturn([]);
+
+    $this->dbSchemaHandler->expects($this->atLeastOnce())
+      ->method('addIndex')
+      ->with('entity_test', 'entity_test__b588603cb9', [['long_index_name', 10]], $this->callback(function($actual_value) use ($expected)  {
+        $this->assertEquals($expected['entity_test']['indexes'], $actual_value['indexes']);
+        $this->assertEquals($expected['entity_test']['fields'], $actual_value['fields']);
+        // If the parameters don't match, the assertions above will throw an
+        // exception.
+        return TRUE;
+      }));
+
+    $this->assertNull(
+      $this->storageSchema->onEntityTypeUpdate($this->entityType, $original_entity_type)
+    );
+  }
+
 }