diff --git a/core/modules/simpletest/tests/fixtures/simpletest_phpunit_run_command_test.php b/core/modules/simpletest/tests/fixtures/simpletest_phpunit_run_command_Test.php
similarity index 100%
rename from core/modules/simpletest/tests/fixtures/simpletest_phpunit_run_command_test.php
rename to core/modules/simpletest/tests/fixtures/simpletest_phpunit_run_command_Test.php
diff --git a/core/tests/Drupal/Tests/Listeners/DrupalStandardsListener.php b/core/tests/Drupal/Tests/Listeners/DrupalStandardsListener.php
index 7f8396f..7196326 100644
--- a/core/tests/Drupal/Tests/Listeners/DrupalStandardsListener.php
+++ b/core/tests/Drupal/Tests/Listeners/DrupalStandardsListener.php
@@ -146,6 +146,7 @@ public function endTest(\PHPUnit_Framework_Test $test, $time) {
     // subclasses.
     if ($test instanceof \PHPUnit_Framework_TestCase) {
       $this->checkValidCoversForTest($test);
+      $this->checkValidFilenameForTest($test);
     }
     elseif ($test instanceof \PHPUnit_Framework_TestSuite) {
       foreach ($test->getGroupDetails() as $tests) {
@@ -156,4 +157,20 @@ public function endTest(\PHPUnit_Framework_Test $test, $time) {
     }
   }
 
+  /**
+   * Ensures that test filenames end with Test.php.
+   *
+   * This method is called from $this::endTest().
+   *
+   * @param \PHPUnit_Framework_TestCase $test
+   *   The test to examine.
+   */
+  protected function checkValidFilenameForTest(\PHPUnit_Framework_TestCase $test) {
+    $filename = (new \ReflectionClass($test))->getFileName();
+    $class = get_class($test);
+    if (!preg_match('/Test.php$/i', $filename)) {
+      $this->fail($test, "The filename for the test class $class not end with Test.php. It uses $filename instead");
+    }
+  }
+
 }