diff --git a/core/modules/simpletest/src/Tests/SimpleTestTest.php b/core/modules/simpletest/src/Tests/SimpleTestTest.php
index 7d39fe6..fe67c7c 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestTest.php
@@ -86,8 +86,8 @@ class: Drupal\Core\Cache\MemoryBackendFactory
    * Ensures the tests selected through the web interface are run and displayed.
    */
   function testWebTestRunner() {
-    $this->pass = t('SimpleTest pass.');
-    $this->fail = t('SimpleTest fail.');
+    $this->passMessage = t('SimpleTest pass.');
+    $this->failMessage = t('SimpleTest fail.');
     $this->valid_permission = 'access administration pages';
     $this->invalid_permission = 'invalid permission';
 
@@ -119,6 +119,9 @@ function testWebTestRunner() {
 
   /**
    * Test to be run and the results confirmed.
+   *
+   * Here we force test results which must match the expected results from
+   * confirmStubResults().
    */
   function stubTest() {
     // Ensure the .htkey file exists since this is only created just before a
@@ -133,17 +136,21 @@ function stubTest() {
 
     // This causes the first of the fifteen passes asserted in
     // confirmStubResults().
-    $this->pass($this->pass);
+    $this->pass($this->passMessage);
+
     // The first three fails are caused by enabling a non-existent module in
-    // setUp(). This causes the fourth of the five fails asserted in
+    // setUp().
+
+    // This causes the fourth of the five fails asserted in
     // confirmStubResults().
-    $this->fail($this->fail);
+    $this->fail($this->failMessage);
 
     // This causes the second to fourth of the fifteen passes asserted in
     // confirmStubResults().
     $user = $this->drupalCreateUser(array($this->valid_permission), 'SimpleTestTest');
     // This causes the fifth of the five fails asserted in confirmStubResults().
     $this->drupalCreateUser(array($this->invalid_permission));
+
     // Test logging in as a user.
     // This causes the fifth to ninth of the fifteen passes asserted in
     // confirmStubResults().
@@ -189,8 +196,8 @@ function assertNothing() {
   function confirmStubTestResults() {
     $this->assertAssertion(t('Enabled modules: %modules', array('%modules' => 'non_existent_module')), 'Other', 'Fail', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->setUp()');
 
-    $this->assertAssertion($this->pass, 'Other', 'Pass', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');
-    $this->assertAssertion($this->fail, 'Other', 'Fail', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');
+    $this->assertAssertion($this->passMessage, 'Other', 'Pass', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');
+    $this->assertAssertion($this->failMessage, 'Other', 'Fail', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');
 
     $this->assertAssertion(t('Created permissions: @perms', array('@perms' => $this->valid_permission)), 'Role', 'Pass', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');
     $this->assertAssertion(t('Invalid permission %permission.', array('%permission' => $this->invalid_permission)), 'Role', 'Fail', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');