diff --git a/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryParserTest.php b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryParserTest.php
index 9df801eb3b..e6cc40b7f9 100644
--- a/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryParserTest.php
+++ b/core/tests/Drupal/Tests/Core/Asset/LibraryDiscoveryParserTest.php
@@ -538,13 +538,13 @@ public function testCssAssert($extension, $exception_message) {
   public function providerTestCssAssert() {
     return [
       // Invalid category.
-      ['css_bad_category', 'Invalid CSS category: bad_category. See https://www.drupal.org/node/2274843.'] ,
+      'css_bad_category' => ['css_bad_category', 'See https://www.drupal.org/node/2274843.'],
 
       // Improper CSS nesting.
-      ['css_bad_nesting', 'CSS must be nested under a category. See https://www.drupal.org/node/2274843.'],
+      'Improper CSS nesting' => ['css_bad_nesting', 'CSS must be nested under a category. See https://www.drupal.org/node/2274843.'],
 
       // Improper nesting with bad key value pairs.
-      ['css_bad_nesting_array', 'CSS files should be specified as key/value pairs, where the values are configuration options. See https://www.drupal.org/node/2274843.'],
+      'Improper CSS nesting array' => ['css_bad_nesting_array', 'CSS files should be specified as key/value pairs, where the values are configuration options. See https://www.drupal.org/node/2274843.'],
     ];
   }