diff --git a/core/modules/update/src/Tests/UpdateTestBase.php b/core/modules/update/src/Tests/UpdateTestBase.php
index fc39d1a3cc..99312208a9 100644
--- a/core/modules/update/src/Tests/UpdateTestBase.php
+++ b/core/modules/update/src/Tests/UpdateTestBase.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\update\Tests;
 
+@trigger_error(__NAMESPACE__ . '\UpdateTestBase is deprecated in Drupal 8.4.0 and will be removed before Drupal 9.0.0. Instead, use \Drupal\Tests\update\Functional\UpdateTestBase', E_USER_DEPRECATED);
+
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\Url;
 use Drupal\simpletest\WebTestBase;
@@ -22,6 +24,9 @@
  * (via the 'update_test_xml_map' variable), and then performs a series of
  * assertions that the report matches our expectations given the specific
  * initial state and availability scenario.
+ *
+ * @deprecated Scheduled for removal in Drupal 9.0.0.
+ *   Use \Drupal\Tests\update\Functional\UpdateTestBase instead.
  */
 abstract class UpdateTestBase extends WebTestBase {
 
diff --git a/core/modules/update/src/Tests/FileTransferAuthorizeFormTest.php b/core/modules/update/tests/src/Functional/FileTransferAuthorizeFormTest.php
similarity index 97%
rename from core/modules/update/src/Tests/FileTransferAuthorizeFormTest.php
rename to core/modules/update/tests/src/Functional/FileTransferAuthorizeFormTest.php
index 9d1819fca3..c314dd5780 100644
--- a/core/modules/update/src/Tests/FileTransferAuthorizeFormTest.php
+++ b/core/modules/update/tests/src/Functional/FileTransferAuthorizeFormTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\update\Tests;
+namespace Drupal\Tests\update\Functional;
 
 /**
  * Tests the Update Manager module upload via authorize.php functionality.
diff --git a/core/modules/update/src/Tests/UpdateContribTest.php b/core/modules/update/tests/src/Functional/UpdateContribTest.php
similarity index 99%
rename from core/modules/update/src/Tests/UpdateContribTest.php
rename to core/modules/update/tests/src/Functional/UpdateContribTest.php
index 81f7117a3a..20d397cd48 100644
--- a/core/modules/update/src/Tests/UpdateContribTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateContribTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\update\Tests;
+namespace Drupal\Tests\update\Functional;
 
 use Drupal\Core\Url;
 use Drupal\Core\Utility\ProjectInfo;
diff --git a/core/modules/update/src/Tests/UpdateCoreTest.php b/core/modules/update/tests/src/Functional/UpdateCoreTest.php
similarity index 99%
rename from core/modules/update/src/Tests/UpdateCoreTest.php
rename to core/modules/update/tests/src/Functional/UpdateCoreTest.php
index b6287c7c04..a693153915 100644
--- a/core/modules/update/src/Tests/UpdateCoreTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateCoreTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\update\Tests;
+namespace Drupal\Tests\update\Functional;
 
 use Drupal\Core\Url;
 
diff --git a/core/modules/update/src/Tests/UpdateDeleteFileIfStaleTest.php b/core/modules/update/tests/src/Functional/UpdateDeleteFileIfStaleTest.php
similarity index 96%
rename from core/modules/update/src/Tests/UpdateDeleteFileIfStaleTest.php
rename to core/modules/update/tests/src/Functional/UpdateDeleteFileIfStaleTest.php
index 99499d77c2..601a6cc2ff 100644
--- a/core/modules/update/src/Tests/UpdateDeleteFileIfStaleTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateDeleteFileIfStaleTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\update\Tests;
+namespace Drupal\Tests\update\Functional;
 
 /**
  * Tests the update_delete_file_if_stale() function.
diff --git a/core/modules/update/src/Tests/UpdateTestBase.php b/core/modules/update/tests/src/Functional/UpdateTestBase.php
similarity index 96%
copy from core/modules/update/src/Tests/UpdateTestBase.php
copy to core/modules/update/tests/src/Functional/UpdateTestBase.php
index fc39d1a3cc..97860ff08f 100644
--- a/core/modules/update/src/Tests/UpdateTestBase.php
+++ b/core/modules/update/tests/src/Functional/UpdateTestBase.php
@@ -1,10 +1,10 @@
 <?php
 
-namespace Drupal\update\Tests;
+namespace Drupal\Tests\update\Functional;
 
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\Url;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Defines some shared functions used by all update tests.
@@ -23,7 +23,7 @@
  * assertions that the report matches our expectations given the specific
  * initial state and availability scenario.
  */
-abstract class UpdateTestBase extends WebTestBase {
+abstract class UpdateTestBase extends BrowserTestBase {
 
   protected function setUp() {
     parent::setUp();
diff --git a/core/modules/update/src/Tests/UpdateUploadTest.php b/core/modules/update/tests/src/Functional/UpdateUploadTest.php
similarity index 98%
rename from core/modules/update/src/Tests/UpdateUploadTest.php
rename to core/modules/update/tests/src/Functional/UpdateUploadTest.php
index 80d3f15d29..a959d9dc0c 100644
--- a/core/modules/update/src/Tests/UpdateUploadTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateUploadTest.php
@@ -1,10 +1,11 @@
 <?php
 
-namespace Drupal\update\Tests;
+namespace Drupal\Tests\update\Functional;
 
 use Drupal\Core\Extension\InfoParserDynamic;
 use Drupal\Core\Updater\Updater;
 use Drupal\Core\Url;
+use Drupal\Tests\TestFileCreationTrait;
 
 /**
  * Tests the Update Manager module's upload and extraction functionality.
@@ -13,6 +14,10 @@
  */
 class UpdateUploadTest extends UpdateTestBase {
 
+  use TestFileCreationTrait {
+    getTestFiles as drupalGetTestFiles;
+  }
+
   /**
    * Modules to enable.
    *