diff --git a/core/modules/content_translation/src/Tests/ContentTestTranslationUITest.php b/core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php
similarity index 93%
rename from core/modules/content_translation/src/Tests/ContentTestTranslationUITest.php
rename to core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php
index 1688f75fd6..0b1de0b204 100644
--- a/core/modules/content_translation/src/Tests/ContentTestTranslationUITest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTestTranslationUITest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Functional;
 
 /**
  * Tests the test content translation UI with the test entity.
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationDisableSettingTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationDisableSettingTest.php
similarity index 96%
rename from core/modules/content_translation/src/Tests/ContentTranslationDisableSettingTest.php
rename to core/modules/content_translation/tests/src/Functional/ContentTranslationDisableSettingTest.php
index a274ad2353..6dffed7444 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationDisableSettingTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationDisableSettingTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Functional;
 
 use Drupal\Tests\BrowserTestBase;
 
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationEnableTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationEnableTest.php
similarity index 91%
rename from core/modules/content_translation/src/Tests/ContentTranslationEnableTest.php
rename to core/modules/content_translation/tests/src/Functional/ContentTranslationEnableTest.php
index 11c816c1d7..99530a7440 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationEnableTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationEnableTest.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Functional;
 
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Test enabling content translation module.
  *
  * @group content_translation
  */
-class ContentTranslationEnableTest extends WebTestBase {
+class ContentTranslationEnableTest extends BrowserTestBase {
 
   /**
    * {@inheritdoc}
@@ -36,7 +36,7 @@ public function testEnable() {
     // No pending updates should be available.
     $this->drupalGet('admin/reports/status');
     $requirement_value = $this->cssSelect("details.system-status-report__entry summary:contains('Entity/field definitions') + div");
-    $this->assertEqual(t('Up to date'), trim((string) $requirement_value[0]));
+    $this->assertEqual(t('Up to date'), trim($requirement_value[0]->getText()));
 
     $this->drupalGet('admin/config/regional/content-language');
     // The node entity type should not be an option because it has no bundles.
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationLanguageChangeTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationLanguageChangeTest.php
similarity index 98%
rename from core/modules/content_translation/src/Tests/ContentTranslationLanguageChangeTest.php
rename to core/modules/content_translation/tests/src/Functional/ContentTranslationLanguageChangeTest.php
index 04bd023cde..ae326ef67b 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationLanguageChangeTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationLanguageChangeTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Functional;
 
 use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\node\Tests\NodeTestBase;
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php
similarity index 98%
rename from core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
rename to core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php
index 7a1c598047..d9b872e7f8 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Functional;
 
 use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
 use Drupal\comment\Tests\CommentTestTrait;
@@ -8,14 +8,14 @@
 use Drupal\Core\Language\Language;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\language\Entity\ContentLanguageSettings;
-use Drupal\simpletest\WebTestBase;
+use Drupal\Tests\BrowserTestBase;
 
 /**
  * Tests the content translation settings UI.
  *
  * @group content_translation
  */
-class ContentTranslationSettingsTest extends WebTestBase {
+class ContentTranslationSettingsTest extends BrowserTestBase {
 
   use CommentTestTrait;
 
@@ -193,7 +193,7 @@ public function testSettingsUI() {
     $elements = $this->xpath('//select[@id="edit-settings-node-article-settings-language-langcode"]/option');
     // Compare values inside the option elements with expected values.
     for ($i = 0; $i < count($elements); $i++) {
-      $this->assertEqual($elements[$i]->attributes()->{'value'}, $expected_elements[$i]);
+      $this->assertEqual($elements[$i]->getText(), $expected_elements[$i]);
     }
   }
 
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationSyncImageTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
similarity index 98%
rename from core/modules/content_translation/src/Tests/ContentTranslationSyncImageTest.php
rename to core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
index 30ff32de52..5f7c9fd9b8 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationSyncImageTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
@@ -1,11 +1,12 @@
 <?php
 
-namespace Drupal\content_translation\Tests;
+namespace Drupal\Tests\content_translation\Functional;
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\file\Entity\File;
+use Drupal\Tests\TestFileCreationTrait;
 
 /**
  * Tests the field synchronization behavior for the image field.
@@ -14,6 +15,10 @@
  */
 class ContentTranslationSyncImageTest extends ContentTranslationTestBase {
 
+  use TestFileCreationTrait {
+    getTestFiles as drupalGetTestFiles;
+  }
+
   /**
    * The cardinality of the image field.
    *
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
index e69329cb5f..223c69d4ed 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\Tests\content_translation\Functional;
 
-use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Entity\EntityChangedInterface;
 use Drupal\Core\Entity\EntityInterface;
@@ -227,10 +226,10 @@ protected function doTestTranslationOverview() {
         $language = new Language(['id' => $langcode]);
         $view_url = $entity->url('canonical', ['language' => $language]);
         $elements = $this->xpath('//table//a[@href=:href]', [':href' => $view_url]);
-        $this->assertEqual($elements[0]->getText(), $entity->getTranslation($langcode)->label(), new FormattableMarkup('Label correctly shown for %language translation.', ['%language' => $langcode]));
+        $this->assertEqual($elements[0]->getText(), $entity->getTranslation($langcode)->label(), format_string('Label correctly shown for %language translation.', ['%language' => $langcode]));
         $edit_path = $entity->url('edit-form', ['language' => $language]);
         $elements = $this->xpath('//table//ul[@class="dropbutton"]/li/a[@href=:href]', [':href' => $edit_path]);
-        $this->assertEqual($elements[0]->getText(), t('Edit'), new FormattableMarkup('Edit link correct for %language translation.', ['%language' => $langcode]));
+        $this->assertEqual($elements[0]->getText(), t('Edit'), format_string('Edit link correct for %language translation.', ['%language' => $langcode]));
       }
     }
   }