diff -u b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
--- b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -170,6 +170,7 @@
     $this->assertNoFieldByName('notexisting');
     $this->assertNoFieldByName('notexisting', NULL);
 
+    // Test that the assertion fails correctly if no value is passed in.
     try {
       $this->assertNoFieldByName('description');
       $this->fail('The "description" field, with no value was not found.');
@@ -177,6 +178,15 @@
     catch (ExpectationException $e) {
       $this->pass('The "description" field, with no value was found.');
     }
+
+    // Test that the assertion fails correctly if a NULL value is passed in.
+    try {
+      $this->assertNoFieldByName('name', NULL);
+      $this->fail('The "name" field was not found.');
+    }
+    catch (ExpectationException $e) {
+      $this->pass('The "name" field was found.');
+    }
   }
 
   /**