diff --git a/core/modules/config/tests/src/FunctionalJavascript/ConfigEntityTest.php b/core/modules/config/tests/src/FunctionalJavascript/ConfigEntityTest.php
index b09d95e..b58c6a8 100644
--- a/core/modules/config/tests/src/FunctionalJavascript/ConfigEntityTest.php
+++ b/core/modules/config/tests/src/FunctionalJavascript/ConfigEntityTest.php
@@ -20,16 +20,16 @@ class ConfigEntityTest extends JavascriptTestBase {
   /**
    * Tests CRUD operations through the UI.
    */
-  function testCRUDUI() {
+  public function testCRUDUI() {
     $this->drupalLogin($this->drupalCreateUser(['administer site configuration']));
 
     $id = strtolower($this->randomMachineName());
     $label1 = $this->randomMachineName();
     $label2 = $this->randomMachineName();
     $label3 = $this->randomMachineName();
-    $message_insert = new FormattableMarkup('%label configuration has been created.', array('%label' => $label1));
-    $message_update = new FormattableMarkup('%label configuration has been updated.', array('%label' => $label2));
-    $message_delete = new FormattableMarkup('The test configuration %label has been deleted.', array('%label' => $label2));
+    $message_insert = new FormattableMarkup('%label configuration has been created.', ['%label' => $label1]);
+    $message_update = new FormattableMarkup('%label configuration has been updated.', ['%label' => $label2]);
+    $message_delete = new FormattableMarkup('The test configuration %label has been deleted.', ['%label' => $label2]);
 
     // Create a configuration entity.
     $this->drupalGet('admin/structure/config_test/add');
@@ -51,7 +51,7 @@ function testCRUDUI() {
     $assert_session->statusCodeEquals(200);
     $assert_session->responseContains($message_insert);
     $assert_session->responseNotContains($message_update);
-    $this->assertNotEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
+    $this->assertNotNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
 
     // Update the configuration entity.
     $this->drupalGet("admin/structure/config_test/manage/$id");
@@ -61,8 +61,8 @@ function testCRUDUI() {
     $assert_session->statusCodeEquals(200);
     $assert_session->responseNotContains($message_insert);
     $assert_session->responseContains($message_update);
-    $this->assertNotEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
-    $this->assertNotEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '/delete"]'));
+    $this->assertNotNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
+    $this->assertNotNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '/delete"]'));
 
     // Delete the configuration entity.
     $this->drupalGet("admin/structure/config_test/manage/$id");
@@ -75,7 +75,7 @@ function testCRUDUI() {
     $assert_session->responseNotContains($message_update);
     $assert_session->responseContains($message_delete);
     $assert_session->responseNotContains($label1);
-    $this->assertEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
+    $this->assertNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
 
     // Re-create a configuration entity.
     $this->drupalGet('admin/structure/config_test/add');
@@ -86,7 +86,7 @@ function testCRUDUI() {
     $assert_session->addressEquals('admin/structure/config_test');
     $assert_session->statusCodeEquals(200);
     $assert_session->responseContains($label1);
-    $this->assertNotEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
+    $this->assertNotNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
 
     // Rename the configuration entity's ID/machine name.
     $new_id = strtolower($this->randomMachineName());
@@ -100,10 +100,10 @@ function testCRUDUI() {
     $assert_session->responseNotContains($label1);
     $assert_session->responseNotContains($label2);
     $assert_session->responseContains($label3);
-    $this->assertEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
+    $this->assertNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
 
     $id = $new_id;
-    $this->assertNotEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
+    $this->assertNotNull($page->find('css', 'a[href="/admin/structure/config_test/manage/' . $id . '"]'));
 
     // Create a configuration entity with '0' machine name.
     $this->drupalGet('admin/structure/config_test/add');
@@ -112,11 +112,11 @@ function testCRUDUI() {
     $button_save->click();
 
     $assert_session->statusCodeEquals(200);
-    $message_insert = new FormattableMarkup('%label configuration has been created.', array('%label' => '0'));
+    $message_insert = new FormattableMarkup('%label configuration has been created.', ['%label' => '0']);
     $assert_session->responseContains($message_insert);
 
-    $this->assertNotEmpty($page->find('css' , 'a[href="/admin/structure/config_test/manage/0"]'));
-    $delete_link = $page->find('css' , 'a[href="/admin/structure/config_test/manage/0/delete"]');
+    $this->assertNotNull($page->find('css', 'a[href="/admin/structure/config_test/manage/0"]'));
+    $delete_link = $page->find('css', 'a[href="/admin/structure/config_test/manage/0/delete"]');
 
     // Expand the options.
     $ul = $delete_link->getParent()->getParent();
@@ -137,8 +137,8 @@ function testCRUDUI() {
     // Test that the dependent element is not shown initially.
     $field_size = $page->findField('size');
     $field_size_value = $page->findField('size_value');
-    $this->assertNotEmpty($field_size);
-    $this->assertEmpty($field_size_value);
+    $this->assertNotNull($field_size);
+    $this->assertNull($field_size_value);
 
     $id = strtolower($this->randomMachineName());
     $field_id->setValue($id);
@@ -148,8 +148,8 @@ function testCRUDUI() {
 
     // Check that the dependent element is shown after selecting a 'size' value.
     $field_size_value = $page->findField('size_value');
-    $this->assertNotEmpty($field_size);
-    $this->assertNotEmpty($field_size_value);
+    $this->assertNotNull($field_size);
+    $this->assertNotNull($field_size_value);
 
     $field_size_value->setValue('medium');
     $button_save->click();