.../search/src/Tests/SearchPageCacheTagsTest.php   | 55 ++++++++++++++++++----
 1 file changed, 47 insertions(+), 8 deletions(-)

diff --git a/core/modules/search/src/Tests/SearchPageCacheTagsTest.php b/core/modules/search/src/Tests/SearchPageCacheTagsTest.php
index e52c214..eb33827 100644
--- a/core/modules/search/src/Tests/SearchPageCacheTagsTest.php
+++ b/core/modules/search/src/Tests/SearchPageCacheTagsTest.php
@@ -13,6 +13,7 @@
  * @group search
  */
 class SearchPageCacheTagsTest extends SearchTestBase {
+
   /**
    * {@inheritdoc}
    */
@@ -25,11 +26,33 @@ class SearchPageCacheTagsTest extends SearchTestBase {
    */
   protected $searchingUser;
 
+  /**
+   * A node that is indexed by the search module.
+   *
+   * @var \Drupal\node\NodeInterface
+   */
+  protected $node;
+
+  /**
+   * {@inheritdoc}
+   */
   protected function setUp() {
     parent::setUp();
 
+    // Enable the page cache.
+    // @todo Remove in https://www.drupal.org/node/606840.
+    $config = $this->config('system.performance');
+    $config->set('cache.page.use_internal', 1);
+    $config->set('cache.page.max_age', 300);
+    $config->save();
+
     // Create user.
     $this->searchingUser = $this->drupalCreateUser(array('search content', 'access user profiles'));
+
+    // Create a node and update the search index.
+    $this->node = $this->drupalCreateNode(['title' => 'bike shed shop']);
+    $this->container->get('plugin.manager.search')->createInstance('node_search')->updateIndex();
+    search_update_totals();
   }
 
   /**
@@ -40,26 +63,42 @@ function testSearchText() {
 
     // Initial page for searching nodes.
     $this->drupalGet('search/node');
-    $cache_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
-    $this->assertTrue(in_array('config:search.page.node_search', $cache_tags));
+    $this->assertCacheTag('config:search.page.node_search');
+    $this->assertCacheTag('search_index:node_search');
 
     // Node search results.
     $edit = array();
     $edit['keys'] = 'bike shed';
     $this->drupalPostForm('search/node', $edit, t('Search'));
-    $cache_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
-    $this->assertTrue(in_array('config:search.page.node_search', $cache_tags));
+    $this->assertText('bike shed shop');
+    $this->assertCacheTag('config:search.page.node_search');
+    $this->assertCacheTag('search_index:node_search');
+
+    // Updating a node should invalidate the search plugin's index cache tag.
+    $this->node->title = 'bike shop';
+    $this->node->save();
+    $this->drupalPostForm('search/node', $edit, t('Search'));
+    $this->assertText('bike shop');
+    $this->assertCacheTag('config:search.page.node_search');
+    $this->assertCacheTag('search_index:node_search');
+
+    // Deleting a node should invalidate the search plugin's index cache tag.
+    $this->node->delete();
+    $this->drupalPostForm('search/node', $edit, t('Search'));
+    $this->assertText('Your search yielded no results.');
+    $this->assertCacheTag('config:search.page.node_search');
+    $this->assertCacheTag('search_index:node_search');
 
     // Initial page for searching users.
     $this->drupalGet('search/user');
-    $cache_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
-    $this->assertTrue(in_array('config:search.page.user_search', $cache_tags));
+    $this->assertCacheTag('config:search.page.user_search');
+    $this->assertCacheTag('search_index:user_search');
 
     // User search results.
     $edit['keys'] = $this->searchingUser->getUsername();
     $this->drupalPostForm('search/user', $edit, t('Search'));
-    $cache_tags = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Tags'));
-    $this->assertTrue(in_array('config:search.page.user_search', $cache_tags));
+    $this->assertCacheTag('config:search.page.user_search');
+    $this->assertCacheTag('search_index:user_search');
   }
 
 }