diff --git a/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php b/core/modules/locale/tests/src/Functional/LocaleConfigTranslationImportTest.php
similarity index 98%
rename from core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
rename to core/modules/locale/tests/src/Functional/LocaleConfigTranslationImportTest.php
index 479a60046b..b0a4b5f28e 100644
--- a/core/modules/locale/src/Tests/LocaleConfigTranslationImportTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleConfigTranslationImportTest.php
@@ -1,9 +1,9 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\locale\Locale;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\language\Entity\ConfigurableLanguage;
 
 /**
@@ -11,7 +11,7 @@
  *
  * @group locale
  */
-class LocaleConfigTranslationImportTest extends WebTestBase {
+class LocaleConfigTranslationImportTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocaleConfigTranslationTest.php b/core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php
similarity index 98%
rename from core/modules/locale/src/Tests/LocaleConfigTranslationTest.php
rename to core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php
index a90dce0c54..701ef585f2 100644
--- a/core/modules/locale/src/Tests/LocaleConfigTranslationTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php
@@ -1,8 +1,8 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\Core\Language\LanguageInterface;
 
 /**
@@ -10,7 +10,7 @@
  *
  * @group locale
  */
-class LocaleConfigTranslationTest extends WebTestBase {
+class LocaleConfigTranslationTest extends BrowserTestBase {
 
   /**
    * The language code used.
diff --git a/core/modules/locale/src/Tests/LocaleExportTest.php b/core/modules/locale/tests/src/Functional/LocaleExportTest.php
similarity index 97%
rename from core/modules/locale/src/Tests/LocaleExportTest.php
rename to core/modules/locale/tests/src/Functional/LocaleExportTest.php
index 54d36e2bc8..05621f6c13 100644
--- a/core/modules/locale/src/Tests/LocaleExportTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleExportTest.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Tests the exportation of locale files.
  *
  * @group locale
  */
-class LocaleExportTest extends WebTestBase {
+class LocaleExportTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocaleFileSystemFormTest.php b/core/modules/locale/tests/src/Functional/LocaleFileSystemFormTest.php
similarity index 91%
rename from core/modules/locale/src/Tests/LocaleFileSystemFormTest.php
rename to core/modules/locale/tests/src/Functional/LocaleFileSystemFormTest.php
index 3ac296abe2..face32e69b 100644
--- a/core/modules/locale/src/Tests/LocaleFileSystemFormTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleFileSystemFormTest.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Tests the locale functionality in the altered file settings form.
  *
  * @group locale
  */
-class LocaleFileSystemFormTest extends WebTestBase {
+class LocaleFileSystemFormTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocaleImportFunctionalTest.php b/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
similarity index 99%
rename from core/modules/locale/src/Tests/LocaleImportFunctionalTest.php
rename to core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
index c1d9a612a9..e3a2c2612e 100644
--- a/core/modules/locale/src/Tests/LocaleImportFunctionalTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
@@ -1,8 +1,8 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\Core\Language\LanguageInterface;
 
 /**
@@ -10,7 +10,7 @@
  *
  * @group locale
  */
-class LocaleImportFunctionalTest extends WebTestBase {
+class LocaleImportFunctionalTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php b/core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php
similarity index 97%
rename from core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php
rename to core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php
index fe99ce2f37..1d5b00548c 100644
--- a/core/modules/locale/src/Tests/LocaleJavascriptTranslationTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleJavascriptTranslationTest.php
@@ -1,9 +1,9 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\Core\Language\LanguageInterface;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\Component\Utility\SafeMarkup;
 
 /**
@@ -11,7 +11,7 @@
  *
  * @group locale
  */
-class LocaleJavascriptTranslationTest extends WebTestBase {
+class LocaleJavascriptTranslationTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocaleLibraryAlterTest.php b/core/modules/locale/tests/src/Functional/LocaleLibraryAlterTest.php
similarity index 85%
rename from core/modules/locale/src/Tests/LocaleLibraryAlterTest.php
rename to core/modules/locale/tests/src/Functional/LocaleLibraryAlterTest.php
index 68996f44a2..5425fc5f4c 100644
--- a/core/modules/locale/src/Tests/LocaleLibraryAlterTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleLibraryAlterTest.php
@@ -1,9 +1,9 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\Core\Asset\AttachedAssets;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Tests localization of the JavaScript libraries.
@@ -12,7 +12,7 @@
  *
  * @group locale
  */
-class LocaleLibraryAlterTest extends WebTestBase {
+class LocaleLibraryAlterTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocalePluralFormatTest.php b/core/modules/locale/tests/src/Functional/LocalePluralFormatTest.php
similarity index 99%
rename from core/modules/locale/src/Tests/LocalePluralFormatTest.php
rename to core/modules/locale/tests/src/Functional/LocalePluralFormatTest.php
index 2315dbd22b..57916caf04 100644
--- a/core/modules/locale/src/Tests/LocalePluralFormatTest.php
+++ b/core/modules/locale/tests/src/Functional/LocalePluralFormatTest.php
@@ -1,16 +1,16 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Tests plural handling for various languages.
  *
  * @group locale
  */
-class LocalePluralFormatTest extends WebTestBase {
+class LocalePluralFormatTest extends BrowserTestBase {
 
   /**
    * An admin user.
diff --git a/core/modules/locale/src/Tests/LocaleTranslateStringTourTest.php b/core/modules/locale/tests/src/Functional/LocaleTranslateStringTourTest.php
similarity index 96%
rename from core/modules/locale/src/Tests/LocaleTranslateStringTourTest.php
rename to core/modules/locale/tests/src/Functional/LocaleTranslateStringTourTest.php
index a4b1656655..397c1c763f 100644
--- a/core/modules/locale/src/Tests/LocaleTranslateStringTourTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleTranslateStringTourTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\tour\Tests\TourTestBase;
 
diff --git a/core/modules/locale/src/Tests/LocaleTranslationUiTest.php b/core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php
similarity index 99%
rename from core/modules/locale/src/Tests/LocaleTranslationUiTest.php
rename to core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php
index 53f77c19fd..90603282ed 100644
--- a/core/modules/locale/src/Tests/LocaleTranslationUiTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php
@@ -1,9 +1,9 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\language\Entity\ConfigurableLanguage;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\Component\Utility\SafeMarkup;
 
@@ -13,7 +13,7 @@
  *
  * @group locale
  */
-class LocaleTranslationUiTest extends WebTestBase {
+class LocaleTranslationUiTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/locale/src/Tests/LocaleUpdateBase.php b/core/modules/locale/tests/src/Functional/LocaleUpdateBase.php
similarity index 98%
rename from core/modules/locale/src/Tests/LocaleUpdateBase.php
rename to core/modules/locale/tests/src/Functional/LocaleUpdateBase.php
index b228a962de..f4c59b2873 100644
--- a/core/modules/locale/src/Tests/LocaleUpdateBase.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateBase.php
@@ -1,16 +1,16 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\file\Entity\File;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 use Drupal\Component\Utility\SafeMarkup;
 
 /**
  * Base class for testing updates to string translations.
  */
-abstract class LocaleUpdateBase extends WebTestBase {
+abstract class LocaleUpdateBase extends BrowserTestBase {
 
   /**
    * Timestamp for an old translation.
diff --git a/core/modules/locale/src/Tests/LocaleUpdateCronTest.php b/core/modules/locale/tests/src/Functional/LocaleUpdateCronTest.php
similarity index 99%
rename from core/modules/locale/src/Tests/LocaleUpdateCronTest.php
rename to core/modules/locale/tests/src/Functional/LocaleUpdateCronTest.php
index 78a14ecac8..b24ce78b96 100644
--- a/core/modules/locale/src/Tests/LocaleUpdateCronTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateCronTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 /**
  * Tests for using cron to update project interface translations.
diff --git a/core/modules/locale/src/Tests/LocaleUpdateDevelopmentReleaseTest.php b/core/modules/locale/tests/src/Functional/LocaleUpdateDevelopmentReleaseTest.php
similarity index 88%
rename from core/modules/locale/src/Tests/LocaleUpdateDevelopmentReleaseTest.php
rename to core/modules/locale/tests/src/Functional/LocaleUpdateDevelopmentReleaseTest.php
index 3d7970bb98..5c972d1ef3 100644
--- a/core/modules/locale/src/Tests/LocaleUpdateDevelopmentReleaseTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateDevelopmentReleaseTest.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Test for proper version fallback in case of a development release.
  *
  * @group language
  */
-class LocaleUpdateDevelopmentReleaseTest extends WebTestBase {
+class LocaleUpdateDevelopmentReleaseTest extends BrowserTestBase {
 
   public static $modules = ['locale', 'locale_test_development_release'];
 
diff --git a/core/modules/locale/src/Tests/LocaleUpdateInterfaceTest.php b/core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php
similarity index 99%
rename from core/modules/locale/src/Tests/LocaleUpdateInterfaceTest.php
rename to core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php
index 32928b1d8b..c6c69c2a97 100644
--- a/core/modules/locale/src/Tests/LocaleUpdateInterfaceTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Component\Utility\SafeMarkup;
diff --git a/core/modules/locale/src/Tests/LocaleUpdateTest.php b/core/modules/locale/tests/src/Functional/LocaleUpdateTest.php
similarity index 99%
rename from core/modules/locale/src/Tests/LocaleUpdateTest.php
rename to core/modules/locale/tests/src/Functional/LocaleUpdateTest.php
index 957419b721..907e572c42 100644
--- a/core/modules/locale/src/Tests/LocaleUpdateTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\locale\Tests;
+namespace Drupal\Tests\locale\Functional;
 
 use Drupal\Core\Language\LanguageInterface;