Update to Drupal 8.1.1. For more information, see https://www.drupal.org/node/2718713

core/modules/simpletest/src/Tests/MissingDependentModuleUnitTest.php

@@ -1,21 +0,0 @@
-<?php
-
-namespace Drupal\simpletest\Tests;
-
-use Drupal\simpletest\KernelTestBase;
-
-/**
- * This test should not load since it requires a module that is not found.
- *
- * @group simpletest
- * @dependencies simpletest_missing_module
- */
-class MissingDependentModuleUnitTest extends KernelTestBase {
-
-  /**
-   * Ensure that this test will not be loaded despite its dependency.
-   */
-  function testFail() {
-    $this->fail('Running test with missing required module.');
-  }
-}