diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 2aeaaa9..a1a1404 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -621,7 +621,7 @@ protected function checkPermissions(array $permissions, $reset = FALSE) {
    *
    * @param $account
    *   User object representing the user to log in.
-   * @param $by_email
+   * @param bool $by_email
    *   Whether to use email for login instead of username.
    *
    * @see drupalCreateUser()
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserLoginTest.php b/core/modules/user/lib/Drupal/user/Tests/UserLoginTest.php
index 7e88b73..5831a30 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserLoginTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserLoginTest.php
@@ -24,29 +24,34 @@ public static function getInfo() {
 
 
   /**
-   * Test that login credentials work.
+   * Test that login credentials work with each method.
    */
   function testLoginByEmail() {
     $account = $this->drupalCreateUser(array());
 
-    // Login via name.
+    // Login test with username only, the default method.
+    // Using e-mail should fail with username only method.
     $this->drupalLogin($account);
+    // Using username should pass.
     $this->assertFailedLogin($account, NULL, TRUE);
 
-    // Login via email only.
+    // Login test with e-mail only method.
     config('user.settings')
       ->set('user_login_method', USER_LOGIN_EMAIL_ONLY)
       ->save();
+    // Using e-mail shoud pass.
     $this->drupalLogin($account, TRUE);
+    // Using username should fail.
     $this->assertFailedLogin($account);
 
-    // Login via name or email.
+    // Login test with username or e-mail method.
     config('user.settings')
       ->set('user_login_method', USER_LOGIN_USERNAME_OR_EMAIL)
       ->save();;
+    // Using e-mail should pass.
     $this->drupalLogin($account, TRUE);
+    // Using username should pass.
     $this->drupalLogin($account);
-
   }
 
   /**
@@ -166,7 +171,7 @@ function testPasswordRehashOnLogin() {
    * @param $flood_trigger
    *   Whether or not to expect that the flood control mechanism will be
    *   triggered.
-   * @param $by_email
+   * @param bool $by_email
    *   Authenticate with email instead of username.
    */
   function assertFailedLogin($account, $flood_trigger = NULL, $by_email = FALSE) {
@@ -193,6 +198,7 @@ function assertFailedLogin($account, $flood_trigger = NULL, $by_email = FALSE) {
         case USER_LOGIN_USERNAME_ONLY:
           $this->assertText(t('Sorry, unrecognized username or password. Have you forgotten your password?'));
           break;
+
         case USER_LOGIN_EMAIL_ONLY:
           if (!$by_email) {
             $this->assertText(t('The e-mail address @email is not valid.', array('@email' => $account->name)));
@@ -201,6 +207,7 @@ function assertFailedLogin($account, $flood_trigger = NULL, $by_email = FALSE) {
             $this->assertText(t('Sorry, unrecognized e-mail address or password. Have you forgotten your password?'));
           }
           break;
+
         case USER_LOGIN_USERNAME_OR_EMAIL:
           $this->assertText(t('Sorry, unrecognized username, e-mail address or password. Have you forgotten your password?'));
         break;
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index caf114d..d0c5800 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -1329,8 +1329,12 @@ function user_login_default_validators() {
 }
 
 /**
- * A FAPI validate handler. Depending on user_login_method, delegates
- * validation to user_login_username_validate() and valid_email_address().
+ * A FAPI validate handler.
+ *
+ * Depending on user_login_method, delegates to valid_email_address(). Sets an
+ * error if username is blocked.
+ *
+ * @see user_login_default_validators()
  */
 function user_login_name_validate($form, &$form_state) {
   if (isset($form_state['values']['name'])) {
@@ -1437,12 +1441,14 @@ function user_login_final_validate($form, &$form_state) {
         case USER_LOGIN_USERNAME_ONLY:
           form_set_error('name', t('Sorry, unrecognized username or password. <a href="@password">Have you forgotten your password?</a>', array('@password' => url('user/password'))));
           break;
+
         case USER_LOGIN_EMAIL_ONLY:
           form_set_error('name', t('Sorry, unrecognized e-mail address or password. <a href="@password">Have you forgotten your password?</a>', array('@password' => url('user/password'))));
           break;
+
         case USER_LOGIN_USERNAME_OR_EMAIL:
           form_set_error('name', t('Sorry, unrecognized username, e-mail address or password. <a href="@password">Have you forgotten your password?</a>', array('@password' => url('user/password'))));
-        break;
+          break;
       }
       watchdog('user', 'Login attempt failed for %user.', array('%user' => $form_state['values']['name']));
     }