core/modules/simpletest/src/WebTestBase.php          |  2 +-
 core/modules/user/src/Tests/UserRegistrationTest.php | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 29271ee..5a05016 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -2748,7 +2748,7 @@ protected function buildUrl($path, array $options = array()) {
    */
   protected function assertCacheTag($expected_cache_tag) {
     $cache_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
-    $this->assertTrue(in_array($expected_cache_tag, $cache_tags));
+    $this->assertTrue(in_array($expected_cache_tag, $cache_tags), sprintf("'%s' cache tag is present.", $expected_cache_tag));
   }
 
 }
diff --git a/core/modules/user/src/Tests/UserRegistrationTest.php b/core/modules/user/src/Tests/UserRegistrationTest.php
index 2666665..24e6972 100644
--- a/core/modules/user/src/Tests/UserRegistrationTest.php
+++ b/core/modules/user/src/Tests/UserRegistrationTest.php
@@ -220,14 +220,23 @@ function testRegistrationWithUserFields() {
     // Check that the field does not appear on the registration form.
     $this->drupalGet('user/register');
     $this->assertNoText($field->label(), 'The field does not appear on user registration form');
+    $this->assertCacheTag('config:core.entity_form_display.user.user.register');
+    $this->assertCacheTag('config:user.settings');
 
     // Have the field appear on the registration form.
     entity_get_form_display('user', 'user', 'register')
       ->setComponent('test_user_field', array('type' => 'test_field_widget'))
       ->save();
+    $check_cache_tags = function() {
+      $this->assertCacheTag('config:core.entity_form_display.user.user.register');
+      $this->assertCacheTag('config:field.field.user.user.test_user_field');
+      $this->assertCacheTag('config:field.storage.user.test_user_field');
+      $this->assertCacheTag('config:user.settings');
+    };
 
     $this->drupalGet('user/register');
     $this->assertText($field->label(), 'The field appears on user registration form');
+    $check_cache_tags();
 
     // Check that validation errors are correctly reported.
     $edit = array();
@@ -236,10 +245,12 @@ function testRegistrationWithUserFields() {
     // Missing input in required field.
     $edit['test_user_field[0][value]'] = '';
     $this->drupalPostForm(NULL, $edit, t('Create new account'));
+    $check_cache_tags();
     $this->assertRaw(t('@name field is required.', array('@name' => $field->label())), 'Field validation error was correctly reported.');
     // Invalid input.
     $edit['test_user_field[0][value]'] = '-1';
     $this->drupalPostForm(NULL, $edit, t('Create new account'));
+    $check_cache_tags();
     $this->assertRaw(t('%name does not accept the value -1.', array('%name' => $field->label())), 'Field validation error was correctly reported.');
 
     // Submit with valid data.
@@ -256,6 +267,7 @@ function testRegistrationWithUserFields() {
     $field_storage->save();
     foreach (array('js', 'nojs') as $js) {
       $this->drupalGet('user/register');
+      $check_cache_tags();
       // Add two inputs.
       $value = rand(1, 255);
       $edit = array();