diff --git a/core/modules/system/tests/src/Kernel/File/ExtensionStreamTest.php b/core/modules/system/tests/src/Kernel/File/ExtensionStreamTest.php
index 52d064f..6b86773 100644
--- a/core/modules/system/tests/src/Kernel/File/ExtensionStreamTest.php
+++ b/core/modules/system/tests/src/Kernel/File/ExtensionStreamTest.php
@@ -4,7 +4,6 @@
 
 use Drupal\Core\Site\Settings;
 use Drupal\KernelTests\KernelTestBase;
-use Symfony\Component\Filesystem\Filesystem;
 
 /**
  * Tests system stream wrapper functions.
@@ -109,6 +108,13 @@ public function providerInvalidUris() {
   }
 
   /**
+   * Tests call of ::dirname() without setting a URI first.
+   */
+  public function testDirnameAsParameter() {
+    $this->assertEquals('module://system', $this->streamWrappers['module']->dirname('module://system/system.admin.css'));
+  }
+
+  /**
    * Test the extension stream wrapper methods.
    *
    * @param string $uri
@@ -132,9 +138,9 @@ public function testStreamWrapperMethods($uri, $dirname, $realpath, $getExternal
     foreach ($case as $method => $expected) {
       list($scheme, ) = explode('://', $uri);
       $this->streamWrappers[$scheme]->setUri($uri);
-      if ($expected instanceof \InvalidArgumentException) {
-        /** @var \InvalidArgumentException $expected */
-        $message = sprintf('Exception thrown: \InvalidArgumentException("%s").', $expected->getMessage());
+      if ($expected instanceof \InvalidArgumentException || $expected instanceof \RuntimeException) {
+        /** @var \Exception $expected */
+        $message = sprintf('Exception thrown: %s("%s").', get_class($expected), $expected->getMessage());
         try {
           $this->streamWrappers[$scheme]->$method();
           $this->fail($message);
@@ -142,14 +148,6 @@ public function testStreamWrapperMethods($uri, $dirname, $realpath, $getExternal
         catch (\InvalidArgumentException $e) {
           $this->assertSame($expected->getMessage(), $e->getMessage(), $message);
         }
-      }
-      else if ($expected instanceof \RuntimeException) {
-        /** @var \RuntimeException $expected */
-        $message = sprintf('Exception thrown: \RuntimeException("%s").', $expected->getMessage());
-        try {
-          $this->streamWrappers[$scheme]->$method();
-          $this->fail($message);
-        }
         catch (\RuntimeException $e) {
           $this->assertSame($expected->getMessage(), $e->getMessage(), $message);
         }
@@ -161,13 +159,6 @@ public function testStreamWrapperMethods($uri, $dirname, $realpath, $getExternal
   }
 
   /**
-   * Test when dirname() is called directly without setting a URI first.
-   */
-  public function testDirnameAsParameter() {
-    $this->assertEquals('module://system', $this->streamWrappers['module']->dirname('module://system/system.admin.css'));
-  }
-
-  /**
    * Provides test cases for testStreamWrapperMethods().
    *
    * @return array[]