diff --git a/core/modules/migrate_drupal_ui/src/Tests/MigrateAccessTest.php b/core/modules/migrate_drupal_ui/tests/src/Functional/MigrateAccessTest.php
similarity index 82%
rename from core/modules/migrate_drupal_ui/src/Tests/MigrateAccessTest.php
rename to core/modules/migrate_drupal_ui/tests/src/Functional/MigrateAccessTest.php
index 04f2048..3c475e2 100644
--- a/core/modules/migrate_drupal_ui/src/Tests/MigrateAccessTest.php
+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/MigrateAccessTest.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace Drupal\migrate_drupal_ui\Tests;
+namespace Drupal\Tests\migrate_drupal_ui\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Tests that only user 1 can access the migrate UI.
  *
  * @group migrate_drupal_ui
  */
-class MigrateAccessTest extends WebTestBase {
+class MigrateAccessTest extends BrowserTestBase {
 
   /**
    * Modules to enable.
diff --git a/core/modules/migrate_drupal_ui/src/Tests/MigrateUpgradeTestBase.php b/core/modules/migrate_drupal_ui/tests/src/Functional/MigrateUpgradeTestBase.php
similarity index 97%
rename from core/modules/migrate_drupal_ui/src/Tests/MigrateUpgradeTestBase.php
rename to core/modules/migrate_drupal_ui/tests/src/Functional/MigrateUpgradeTestBase.php
index 85a9e79..b5a7c8a 100644
--- a/core/modules/migrate_drupal_ui/src/Tests/MigrateUpgradeTestBase.php
+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/MigrateUpgradeTestBase.php
@@ -1,16 +1,15 @@
 <?php
 
-namespace Drupal\migrate_drupal_ui\Tests;
+namespace Drupal\Tests\migrate_drupal_ui\Functional;
 
 use Drupal\Core\Database\Database;
 use Drupal\migrate\Plugin\MigrateIdMapInterface;
 use Drupal\migrate_drupal\MigrationConfigurationTrait;
-use Drupal\simpletest\WebTestBase;
-
+use Drupal\Tests\BrowserTestBase;
 /**
  * Provides a base class for testing migration upgrades in the UI.
  */
-abstract class MigrateUpgradeTestBase extends WebTestBase {
+abstract class MigrateUpgradeTestBase extends BrowserTestBase {
   use MigrationConfigurationTrait;
 
   /**
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/MigrateUpgrade6Test.php b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/MigrateUpgrade6Test.php
similarity index 93%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/MigrateUpgrade6Test.php
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/MigrateUpgrade6Test.php
index 404f21b..33d2727 100644
--- a/core/modules/migrate_drupal_ui/src/Tests/d6/MigrateUpgrade6Test.php
+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/MigrateUpgrade6Test.php
@@ -1,8 +1,8 @@
 <?php
 
-namespace Drupal\migrate_drupal_ui\Tests\d6;
+namespace Drupal\Tests\migrate_drupal_ui\Functional\d6;
 
-use Drupal\migrate_drupal_ui\Tests\MigrateUpgradeTestBase;
+use Drupal\Tests\migrate_drupal_ui\Functional\MigrateUpgradeTestBase;
 use Drupal\user\Entity\User;
 
 /**
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/html-1.txt b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/html-1.txt
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/html-1.txt
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/html-1.txt
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-1.png b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-1.png
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-1.png
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-1.png
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-2.jpg b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-2.jpg
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-2.jpg
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-2.jpg
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-test.gif b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-test.gif
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-test.gif
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-test.gif
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-test.jpg b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-test.jpg
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-test.jpg
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-test.jpg
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-test.png b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-test.png
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/core/modules/simpletest/files/image-test.png
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/core/modules/simpletest/files/image-test.png
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d6/files/tmp/some-temp-file.jpg b/core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/tmp/some-temp-file.jpg
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d6/files/tmp/some-temp-file.jpg
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d6/files/tmp/some-temp-file.jpg
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d7/MigrateUpgrade7Test.php b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php
similarity index 94%
rename from core/modules/migrate_drupal_ui/src/Tests/d7/MigrateUpgrade7Test.php
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php
index 86f1ca9..a0bc1be 100644
--- a/core/modules/migrate_drupal_ui/src/Tests/d7/MigrateUpgrade7Test.php
+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/MigrateUpgrade7Test.php
@@ -1,8 +1,8 @@
 <?php
 
-namespace Drupal\migrate_drupal_ui\Tests\d7;
+namespace Drupal\Tests\migrate_drupal_ui\Functional\d7;
 
-use Drupal\migrate_drupal_ui\Tests\MigrateUpgradeTestBase;
+use Drupal\Tests\migrate_drupal_ui\Functional\MigrateUpgradeTestBase;
 use Drupal\user\Entity\User;
 
 /**
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d7/files/sites/default/files/cube.jpeg b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/files/sites/default/files/cube.jpeg
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d7/files/sites/default/files/cube.jpeg
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d7/files/sites/default/files/cube.jpeg
diff --git a/core/modules/migrate_drupal_ui/src/Tests/d7/files/sites/default/files/ds9.txt b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/files/sites/default/files/ds9.txt
similarity index 100%
rename from core/modules/migrate_drupal_ui/src/Tests/d7/files/sites/default/files/ds9.txt
rename to core/modules/migrate_drupal_ui/tests/src/Functional/d7/files/sites/default/files/ds9.txt