.../src/Tests/Cache/AssertPageCacheTagsTrait.php   | 23 ++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/core/modules/system/src/Tests/Cache/AssertPageCacheTagsTrait.php b/core/modules/system/src/Tests/Cache/AssertPageCacheTagsTrait.php
index 86192ed..6fed903 100644
--- a/core/modules/system/src/Tests/Cache/AssertPageCacheTagsTrait.php
+++ b/core/modules/system/src/Tests/Cache/AssertPageCacheTagsTrait.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\system\Tests\Cache;
+
 use Drupal\Core\Url;
 
 /**
@@ -15,7 +16,6 @@
  */
 trait AssertPageCacheTagsTrait {
 
-
   /**
    * Enables page caching.
    */
@@ -27,25 +27,32 @@ protected function enablePageCaching() {
   }
 
   /**
-   * Fills page cache for the given path, verify cache tags on page cache hit.
+   * Asserts page cache miss, then hit for the given URL; checks cache tags.
    *
    * @param \Drupal\Core\Url $url
-   *   The url
-   * @param $expected_tags
-   *   The expected cache tags for the page cache entry of the given $path.
+   *   The URL to test.
+   * @param string[] $expected_tags
+   *   The expected cache tags for the given URL.
    */
-  protected function assertPageCacheTags(Url $url, $expected_tags) {
+  protected function assertPageCacheTags(Url $url, array $expected_tags) {
+    $absolute_url = $url->setAbsolute()->toString();
     sort($expected_tags);
-    $this->drupalGet($url->setAbsolute()->toString());
+
+    // Assert cache miss + expected cache tags.
+    $this->drupalGet($absolute_url);
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS');
     $actual_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
     sort($actual_tags);
     $this->assertIdentical($actual_tags, $expected_tags);
-    $this->drupalGet($url->setAbsolute()->toString());
+
+    // Assert cache hit + expected cache tags.
+    $this->drupalGet($absolute_url);
     $actual_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
     sort($actual_tags);
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT');
     $this->assertIdentical($actual_tags, $expected_tags);
+
+    // Assert page cache item + expected cache tags.
     $cid_parts = array($url->setAbsolute()->toString(), 'html');
     $cid = implode(':', $cid_parts);
     $cache_entry = \Drupal::cache('render')->get($cid);