diff --git a/core/core.libraries.yml b/core/core.libraries.yml
index c8ab09e..2a47204 100644
--- a/core/core.libraries.yml
+++ b/core/core.libraries.yml
@@ -403,10 +403,10 @@ jquery.once:
 
 jquery.ui:
   remote: https://github.com/jquery/jquery-ui
-  version: &jquery_ui_version 1.11.2
+  version: &jquery_ui_version 1.11.4
   license: &jquery_ui_license
     name: MIT
-    url: https://github.com/jquery/jquery-ui/blob/1.11.2/MIT-LICENSE.txt
+    url: https://github.com/jquery/jquery-ui/blob/1.11.4/MIT-LICENSE.txt
     gpl-compatible: true
   js:
     assets/vendor/jquery.ui/ui/core-min.js: { weight: -11, minified: true }
diff --git a/core/tests/Drupal/Tests/UnitTestCase.php b/core/tests/Drupal/Tests/UnitTestCase.php
index c15bff2..551c5c4 100644
--- a/core/tests/Drupal/Tests/UnitTestCase.php
+++ b/core/tests/Drupal/Tests/UnitTestCase.php
@@ -37,6 +37,12 @@
    */
   protected function setUp() {
     parent::setUp();
+
+    // Ensure that tests are in the Drupal\Tests namespace.
+    if (strpos(__NAMESPACE__, 'Drupal\Tests', 0) !== 0) {
+      throw new \Exception('Unit tests must be in the "Drupal\Tests" namespace.');
+    }
+
     // Ensure that an instantiated container in the global state of \Drupal from
     // a previous test does not leak into this test.
     \Drupal::unsetContainer();