diff --git a/core/modules/tracker/tests/src/Functional/TrackerTest.php b/core/modules/tracker/tests/src/Functional/TrackerCommentTest.php
similarity index 57%
copy from core/modules/tracker/tests/src/Functional/TrackerTest.php
copy to core/modules/tracker/tests/src/Functional/TrackerCommentTest.php
index 17f95ee..2a90fd1 100644
--- a/core/modules/tracker/tests/src/Functional/TrackerTest.php
+++ b/core/modules/tracker/tests/src/Functional/TrackerCommentTest.php
@@ -6,109 +6,43 @@
 use Drupal\comment\Tests\CommentTestTrait;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\EventSubscriber\MainContentViewSubscriber;
-use Drupal\Core\Session\AccountInterface;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\node\Entity\Node;
-use Drupal\system\Tests\Cache\AssertPageCacheContextsAndTagsTrait;
-use Drupal\Tests\BrowserTestBase;
 
 /**
  * Create and delete nodes and check for their display in the tracker listings.
  *
  * @group tracker
  */
-class TrackerTest extends BrowserTestBase {
+class TrackerCommentTest extends TrackerTest {
 
   use CommentTestTrait;
-  use AssertPageCacheContextsAndTagsTrait;
 
   /**
    * Modules to enable.
    *
    * @var array
    */
-  public static $modules = ['block', 'comment', 'tracker', 'history', 'node_test'];
+  protected static $modules = ['block', 'comment', 'tracker', 'history', 'node_test'];
 
   /**
-   * The main user for testing.
+   * Permissions to give to test users.
    *
-   * @var \Drupal\user\UserInterface
+   * @var array
    */
-  protected $user;
-
-  /**
-   * A second user that will 'create' comments and nodes.
-   *
-   * @var \Drupal\user\UserInterface
-   */
-  protected $otherUser;
+  protected $permissions = ['access comments', 'create page content', 'post comments', 'skip comment approval'];
 
   protected function setUp() {
     parent::setUp();
 
-    $this->drupalCreateContentType(['type' => 'page', 'name' => 'Basic page']);
-
-    $permissions = ['access comments', 'create page content', 'post comments', 'skip comment approval'];
-    $this->user = $this->drupalCreateUser($permissions);
-    $this->otherUser = $this->drupalCreateUser($permissions);
     $this->addDefaultCommentField('node', 'page');
-    user_role_grant_permissions(AccountInterface::ANONYMOUS_ROLE, [
-      'access content',
-      'access user profiles',
-    ]);
-    $this->drupalPlaceBlock('local_tasks_block', ['id' => 'page_tabs_block']);
-    $this->drupalPlaceBlock('local_actions_block', ['id' => 'page_actions_block']);
   }
 
   /**
    * Tests for the presence of nodes on the global tracker listing.
    */
   public function testTrackerAll() {
-    $this->drupalLogin($this->user);
-
-    $unpublished = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-      'status' => 0,
-    ]);
-    $published = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-      'status' => 1,
-    ]);
-
-    $this->drupalGet('activity');
-    $this->assertNoText($unpublished->label(), 'Unpublished node does not show up in the tracker listing.');
-    $this->assertText($published->label(), 'Published node shows up in the tracker listing.');
-    $this->assertLink(t('My recent content'), 0, 'User tab shows up on the global tracker page.');
-
-    // Assert cache contexts, specifically the pager and node access contexts.
-    $this->assertCacheContexts(['languages:language_interface', 'route', 'theme', 'url.query_args:' . MainContentViewSubscriber::WRAPPER_FORMAT, 'url.query_args.pagers:0', 'user.node_grants:view', 'user']);
-    // Assert cache tags for the action/tabs blocks, visible node, and node list
-    // cache tag.
-    $expected_tags = Cache::mergeTags($published->getCacheTags(), $published->getOwner()->getCacheTags());
-    // Because the 'user.permissions' cache context is being optimized away.
-    $role_tags = [];
-    foreach ($this->user->getRoles() as $rid) {
-      $role_tags[] = "config:user.role.$rid";
-    }
-    $expected_tags = Cache::mergeTags($expected_tags, $role_tags);
-    $block_tags = [
-      'block_view',
-      'config:block.block.page_actions_block',
-      'config:block.block.page_tabs_block',
-      'config:block_list',
-    ];
-    $expected_tags = Cache::mergeTags($expected_tags, $block_tags);
-    $additional_tags = [
-      'node_list',
-      'rendered',
-    ];
-    $expected_tags = Cache::mergeTags($expected_tags, $additional_tags);
-    $this->assertCacheTags($expected_tags);
-
-    // Delete a node and ensure it no longer appears on the tracker.
-    $published->delete();
-    $this->drupalGet('activity');
-    $this->assertNoText($published->label(), 'Deleted node does not show up in the tracker listing.');
+    parent::testTrackerAll();
 
     // Test proper display of time on activity page when comments are disabled.
     // Disable comments.
@@ -130,18 +64,8 @@ public function testTrackerAll() {
    * Tests for the presence of nodes on a user's tracker listing.
    */
   public function testTrackerUser() {
-    $this->drupalLogin($this->user);
+    parent::testTrackerUser();
 
-    $unpublished = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-      'uid' => $this->user->id(),
-      'status' => 0,
-    ]);
-    $my_published = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-      'uid' => $this->user->id(),
-      'status' => 1,
-    ]);
     $other_published_no_comment = $this->drupalCreateNode([
       'title' => $this->randomMachineName(8),
       'uid' => $this->otherUser->id(),
@@ -159,8 +83,6 @@ public function testTrackerUser() {
     $this->drupalPostForm('comment/reply/node/' . $other_published_my_comment->id() . '/comment', $comment, t('Save'));
 
     $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertNoText($unpublished->label(), "Unpublished nodes do not show up in the user's tracker listing.");
-    $this->assertText($my_published->label(), "Published nodes show up in the user's tracker listing.");
     $this->assertNoText($other_published_no_comment->label(), "Another user's nodes do not show up in the user's tracker listing.");
     $this->assertText($other_published_my_comment->label(), "Nodes that the user has commented on appear in the user's tracker listing.");
 
@@ -191,13 +113,6 @@ public function testTrackerUser() {
     $expected_tags = Cache::mergeTags($expected_tags, $additional_tags);
 
     $this->assertCacheTags($expected_tags);
-    $this->assertCacheContexts(['languages:language_interface', 'route', 'theme', 'url.query_args:' . MainContentViewSubscriber::WRAPPER_FORMAT, 'url.query_args.pagers:0', 'user', 'user.node_grants:view']);
-
-    $this->assertLink($my_published->label());
-    $this->assertNoLink($unpublished->label());
-    // Verify that title and tab title have been set correctly.
-    $this->assertText('Activity', 'The user activity tab has the name "Activity".');
-    $this->assertTitle(t('@name | @site', ['@name' => $this->user->getUsername(), '@site' => $this->config('system.site')->get('name')]), 'The user tracker page has the correct page title.');
 
     // Verify that unpublished comments are removed from the tracker.
     $admin_user = $this->drupalCreateUser(['post comments', 'administer comments', 'access user profiles']);
@@ -205,40 +120,13 @@ public function testTrackerUser() {
     $this->drupalPostForm('comment/1/edit', ['status' => CommentInterface::NOT_PUBLISHED], t('Save'));
     $this->drupalGet('user/' . $this->user->id() . '/activity');
     $this->assertNoText($other_published_my_comment->label(), 'Unpublished comments are not counted on the tracker listing.');
-
-    // Test escaping of title on user's tracker tab.
-    \Drupal::service('module_installer')->install(['user_hooks_test']);
-    Cache::invalidateTags(['rendered']);
-    \Drupal::state()->set('user_hooks_test_user_format_name_alter', TRUE);
-    $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertEscaped('<em>' . $this->user->id() . '</em>');
-
-    \Drupal::state()->set('user_hooks_test_user_format_name_alter_safe', TRUE);
-    Cache::invalidateTags(['rendered']);
-    $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertNoEscaped('<em>' . $this->user->id() . '</em>');
-    $this->assertRaw('<em>' . $this->user->id() . '</em>');
   }
 
   /**
    * Tests the metadata for the "new"/"updated" indicators.
    */
   public function testTrackerHistoryMetadata() {
-    $this->drupalLogin($this->user);
-
-    // Create a page node.
-    $edit = [
-      'title' => $this->randomMachineName(8),
-    ];
-    $node = $this->drupalCreateNode($edit);
-
-    // Verify that the history metadata is present.
-    $this->drupalGet('activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
-    $this->drupalGet('activity/' . $this->user->id());
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
-    $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
+    $node = parent::testTrackerHistoryMetadata();
 
     // Add a comment to the page, make sure it is created after the node by
     // sleeping for one second, to ensure the last comment timestamp is
@@ -256,19 +144,19 @@ public function testTrackerHistoryMetadata() {
 
     // Verify that the history metadata is updated.
     $this->drupalGet('activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
+    $this->assertCommentHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
     $this->drupalGet('activity/' . $this->user->id());
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
+    $this->assertCommentHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
     $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
+    $this->assertCommentHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
 
     // Log out, now verify that the metadata is still there, but the library is
     // not.
     $this->drupalLogout();
     $this->drupalGet('activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp, FALSE);
+    $this->assertCommentHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp, FALSE);
     $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp, FALSE);
+    $this->assertCommentHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp, FALSE);
   }
 
   /**
@@ -391,34 +279,6 @@ public function testTrackerCronIndexing() {
   }
 
   /**
-   * Tests that publish/unpublish works at admin/content/node.
-   */
-  public function testTrackerAdminUnpublish() {
-    \Drupal::service('module_installer')->install(['views']);
-    \Drupal::service('router.builder')->rebuild();
-    $admin_user = $this->drupalCreateUser(['access content overview', 'administer nodes', 'bypass node access']);
-    $this->drupalLogin($admin_user);
-
-    $node = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(),
-    ]);
-
-    // Assert that the node is displayed.
-    $this->drupalGet('activity');
-    $this->assertText($node->label(), 'A node is displayed on the tracker listing pages.');
-
-    // Unpublish the node and ensure that it's no longer displayed.
-    $edit = [
-      'action' => 'node_unpublish_action',
-      'node_bulk_form[0]' => $node->id(),
-    ];
-    $this->drupalPostForm('admin/content', $edit, t('Apply to selected items'));
-
-    $this->drupalGet('activity');
-    $this->assertText(t('No content available.'), 'A node is displayed on the tracker listing pages.');
-  }
-
-  /**
    * Passes if the appropriate history metadata exists.
    *
    * Verify the data-history-node-id, data-history-node-timestamp and
@@ -438,10 +298,8 @@ public function testTrackerAdminUnpublish() {
    * @param bool $library_is_present
    *   Whether the drupal.tracker-history library should be present or not.
    */
-  public function assertHistoryMetadata($node_id, $node_timestamp, $node_last_comment_timestamp, $library_is_present = TRUE) {
-    $settings = $this->getDrupalSettings();
-    $this->assertIdentical($library_is_present, isset($settings['ajaxPageState']) && in_array('tracker/history', explode(',', $settings['ajaxPageState']['libraries'])), 'drupal.tracker-history library is present.');
-    $this->assertIdentical(1, count($this->xpath('//table/tbody/tr/td[@data-history-node-id="' . $node_id . '" and @data-history-node-timestamp="' . $node_timestamp . '"]')), 'Tracker table cell contains the data-history-node-id and data-history-node-timestamp attributes for the node.');
+  public function assertCommentHistoryMetadata($node_id, $node_timestamp, $node_last_comment_timestamp, $library_is_present = TRUE) {
+    $this->assertHistoryMetadata($node_id, $node_timestamp, $library_is_present);
     $this->assertIdentical(1, count($this->xpath('//table/tbody/tr/td[@data-history-node-last-comment-timestamp="' . $node_last_comment_timestamp . '"]')), 'Tracker table cell contains the data-history-node-last-comment-timestamp attribute for the node.');
   }
 
diff --git a/core/modules/tracker/tests/src/Functional/TrackerNodeAccessTest.php b/core/modules/tracker/tests/src/Functional/TrackerNodeAccessTest.php
index 2b320ae..4dd32df 100644
--- a/core/modules/tracker/tests/src/Functional/TrackerNodeAccessTest.php
+++ b/core/modules/tracker/tests/src/Functional/TrackerNodeAccessTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
 use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\node\Entity\NodeType;
 use Drupal\Tests\BrowserTestBase;
 
@@ -61,6 +62,8 @@ public function testTrackerNodeAccess() {
     $this->drupalGet('user/' . $access_user->id() . '/activity');
     $this->assertText($private_node->getTitle(), 'Private node is visible to user with private access.');
     $this->assertText($public_node->getTitle(), 'Public node is visible to user with private access.');
+    // Comments column displayed.
+    $this->assertSession()->pageTextContains('Comments');
 
     // User without access should not see private node.
     $this->drupalLogin($no_access_user);
@@ -70,6 +73,23 @@ public function testTrackerNodeAccess() {
     $this->drupalGet('user/' . $access_user->id() . '/activity');
     $this->assertNoText($private_node->getTitle(), 'Private node is not visible to user without private access.');
     $this->assertText($public_node->getTitle(), 'Public node is visible to user without private access.');
+
+    // Ensure module pages works when comment module uninstalled.
+    $field = FieldStorageConfig::loadByName('node', 'comment');
+    $field->delete();
+    field_purge_batch(10);
+    /** @var \Drupal\Core\Extension\ModuleInstallerInterface $service */
+    $service = \Drupal::service('module_installer');
+    $service->uninstall(['comment']);
+    $this->drupalLogin($access_user);
+    $this->drupalGet('activity');
+    $this->assertSession()->pageTextContains($private_node->getTitle());
+    // Comments column hidden.
+    $this->assertSession()->pageTextNotContains('Comments');
+    $this->drupalGet('user/' . $access_user->id() . '/activity');
+    $this->assertSession()->pageTextContains($private_node->getTitle());
+    // Comments column hidden.
+    $this->assertSession()->pageTextNotContains('Comments');
   }
 
 }
diff --git a/core/modules/tracker/tests/src/Functional/TrackerTest.php b/core/modules/tracker/tests/src/Functional/TrackerTest.php
index 17f95ee..333a872 100644
--- a/core/modules/tracker/tests/src/Functional/TrackerTest.php
+++ b/core/modules/tracker/tests/src/Functional/TrackerTest.php
@@ -2,13 +2,9 @@
 
 namespace Drupal\Tests\tracker\Functional;
 
-use Drupal\comment\CommentInterface;
-use Drupal\comment\Tests\CommentTestTrait;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\EventSubscriber\MainContentViewSubscriber;
 use Drupal\Core\Session\AccountInterface;
-use Drupal\field\Entity\FieldStorageConfig;
-use Drupal\node\Entity\Node;
 use Drupal\system\Tests\Cache\AssertPageCacheContextsAndTagsTrait;
 use Drupal\Tests\BrowserTestBase;
 
@@ -19,7 +15,6 @@
  */
 class TrackerTest extends BrowserTestBase {
 
-  use CommentTestTrait;
   use AssertPageCacheContextsAndTagsTrait;
 
   /**
@@ -27,7 +22,14 @@ class TrackerTest extends BrowserTestBase {
    *
    * @var array
    */
-  public static $modules = ['block', 'comment', 'tracker', 'history', 'node_test'];
+  protected static $modules = ['block', 'tracker', 'history', 'node_test'];
+
+  /**
+   * Permissions to give to test users.
+   *
+   * @var array
+   */
+  protected $permissions = ['create page content'];
 
   /**
    * The main user for testing.
@@ -48,10 +50,8 @@ protected function setUp() {
 
     $this->drupalCreateContentType(['type' => 'page', 'name' => 'Basic page']);
 
-    $permissions = ['access comments', 'create page content', 'post comments', 'skip comment approval'];
-    $this->user = $this->drupalCreateUser($permissions);
-    $this->otherUser = $this->drupalCreateUser($permissions);
-    $this->addDefaultCommentField('node', 'page');
+    $this->user = $this->drupalCreateUser($this->permissions);
+    $this->otherUser = $this->drupalCreateUser($this->permissions);
     user_role_grant_permissions(AccountInterface::ANONYMOUS_ROLE, [
       'access content',
       'access user profiles',
@@ -109,21 +109,6 @@ public function testTrackerAll() {
     $published->delete();
     $this->drupalGet('activity');
     $this->assertNoText($published->label(), 'Deleted node does not show up in the tracker listing.');
-
-    // Test proper display of time on activity page when comments are disabled.
-    // Disable comments.
-    FieldStorageConfig::loadByName('node', 'comment')->delete();
-    $node = $this->drupalCreateNode([
-      // This title is required to trigger the custom changed time set in the
-      // node_test module. This is needed in order to ensure a sufficiently
-      // large 'time ago' interval that isn't numbered in seconds.
-      'title' => 'testing_node_presave',
-      'status' => 1,
-    ]);
-
-    $this->drupalGet('activity');
-    $this->assertText($node->label(), 'Published node shows up in the tracker listing.');
-    $this->assertText(\Drupal::service('date.formatter')->formatTimeDiffSince($node->getChangedTime()), 'The changed time was displayed on the tracker listing.');
   }
 
   /**
@@ -142,35 +127,16 @@ public function testTrackerUser() {
       'uid' => $this->user->id(),
       'status' => 1,
     ]);
-    $other_published_no_comment = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-      'uid' => $this->otherUser->id(),
-      'status' => 1,
-    ]);
-    $other_published_my_comment = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-      'uid' => $this->otherUser->id(),
-      'status' => 1,
-    ]);
-    $comment = [
-      'subject[0][value]' => $this->randomMachineName(),
-      'comment_body[0][value]' => $this->randomMachineName(20),
-    ];
-    $this->drupalPostForm('comment/reply/node/' . $other_published_my_comment->id() . '/comment', $comment, t('Save'));
 
     $this->drupalGet('user/' . $this->user->id() . '/activity');
     $this->assertNoText($unpublished->label(), "Unpublished nodes do not show up in the user's tracker listing.");
     $this->assertText($my_published->label(), "Published nodes show up in the user's tracker listing.");
-    $this->assertNoText($other_published_no_comment->label(), "Another user's nodes do not show up in the user's tracker listing.");
-    $this->assertText($other_published_my_comment->label(), "Nodes that the user has commented on appear in the user's tracker listing.");
 
     // Assert cache contexts.
     $this->assertCacheContexts(['languages:language_interface', 'route', 'theme', 'url.query_args:' . MainContentViewSubscriber::WRAPPER_FORMAT, 'url.query_args.pagers:0', 'user', 'user.node_grants:view']);
     // Assert cache tags for the visible nodes (including owners) and node list
     // cache tag.
     $expected_tags = Cache::mergeTags($my_published->getCacheTags(), $my_published->getOwner()->getCacheTags());
-    $expected_tags = Cache::mergeTags($expected_tags, $other_published_my_comment->getCacheTags());
-    $expected_tags = Cache::mergeTags($expected_tags, $other_published_my_comment->getOwner()->getCacheTags());
     // Because the 'user.permissions' cache context is being optimized away.
     $role_tags = [];
     foreach ($this->user->getRoles() as $rid) {
@@ -199,13 +165,6 @@ public function testTrackerUser() {
     $this->assertText('Activity', 'The user activity tab has the name "Activity".');
     $this->assertTitle(t('@name | @site', ['@name' => $this->user->getUsername(), '@site' => $this->config('system.site')->get('name')]), 'The user tracker page has the correct page title.');
 
-    // Verify that unpublished comments are removed from the tracker.
-    $admin_user = $this->drupalCreateUser(['post comments', 'administer comments', 'access user profiles']);
-    $this->drupalLogin($admin_user);
-    $this->drupalPostForm('comment/1/edit', ['status' => CommentInterface::NOT_PUBLISHED], t('Save'));
-    $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertNoText($other_published_my_comment->label(), 'Unpublished comments are not counted on the tracker listing.');
-
     // Test escaping of title on user's tracker tab.
     \Drupal::service('module_installer')->install(['user_hooks_test']);
     Cache::invalidateTags(['rendered']);
@@ -234,107 +193,13 @@ public function testTrackerHistoryMetadata() {
 
     // Verify that the history metadata is present.
     $this->drupalGet('activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
+    $this->assertHistoryMetadata($node->id(), $node->getChangedTime());
     $this->drupalGet('activity/' . $this->user->id());
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
+    $this->assertHistoryMetadata($node->id(), $node->getChangedTime());
     $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
+    $this->assertHistoryMetadata($node->id(), $node->getChangedTime());
 
-    // Add a comment to the page, make sure it is created after the node by
-    // sleeping for one second, to ensure the last comment timestamp is
-    // different from before.
-    $comment = [
-      'subject[0][value]' => $this->randomMachineName(),
-      'comment_body[0][value]' => $this->randomMachineName(20),
-    ];
-    sleep(1);
-    $this->drupalPostForm('comment/reply/node/' . $node->id() . '/comment', $comment, t('Save'));
-    // Reload the node so that comment.module's hook_node_load()
-    // implementation can set $node->last_comment_timestamp for the freshly
-    // posted comment.
-    $node = Node::load($node->id());
-
-    // Verify that the history metadata is updated.
-    $this->drupalGet('activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
-    $this->drupalGet('activity/' . $this->user->id());
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
-    $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp);
-
-    // Log out, now verify that the metadata is still there, but the library is
-    // not.
-    $this->drupalLogout();
-    $this->drupalGet('activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp, FALSE);
-    $this->drupalGet('user/' . $this->user->id() . '/activity');
-    $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->get('comment')->last_comment_timestamp, FALSE);
-  }
-
-  /**
-   * Tests for ordering on a users tracker listing when comments are posted.
-   */
-  public function testTrackerOrderingNewComments() {
-    $this->drupalLogin($this->user);
-
-    $node_one = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-    ]);
-
-    $node_two = $this->drupalCreateNode([
-      'title' => $this->randomMachineName(8),
-    ]);
-
-    // Now get otherUser to track these pieces of content.
-    $this->drupalLogin($this->otherUser);
-
-    // Add a comment to the first page.
-    $comment = [
-      'subject[0][value]' => $this->randomMachineName(),
-      'comment_body[0][value]' => $this->randomMachineName(20),
-    ];
-    $this->drupalPostForm('comment/reply/node/' . $node_one->id() . '/comment', $comment, t('Save'));
-
-    // If the comment is posted in the same second as the last one then Drupal
-    // can't tell the difference, so we wait one second here.
-    sleep(1);
-
-    // Add a comment to the second page.
-    $comment = [
-      'subject[0][value]' => $this->randomMachineName(),
-      'comment_body[0][value]' => $this->randomMachineName(20),
-    ];
-    $this->drupalPostForm('comment/reply/node/' . $node_two->id() . '/comment', $comment, t('Save'));
-
-    // We should at this point have in our tracker for otherUser:
-    // 1. node_two
-    // 2. node_one
-    // Because that's the reverse order of the posted comments.
-
-    // Now we're going to post a comment to node_one which should jump it to the
-    // top of the list.
-
-    $this->drupalLogin($this->user);
-    // If the comment is posted in the same second as the last one then Drupal
-    // can't tell the difference, so we wait one second here.
-    sleep(1);
-
-    // Add a comment to the second page.
-    $comment = [
-      'subject[0][value]' => $this->randomMachineName(),
-      'comment_body[0][value]' => $this->randomMachineName(20),
-    ];
-    $this->drupalPostForm('comment/reply/node/' . $node_one->id() . '/comment', $comment, t('Save'));
-
-    // Switch back to the otherUser and assert that the order has swapped.
-    $this->drupalLogin($this->otherUser);
-    $this->drupalGet('user/' . $this->otherUser->id() . '/activity');
-    // This is a cheeky way of asserting that the nodes are in the right order
-    // on the tracker page.
-    // It's almost certainly too brittle.
-    $pattern = '/' . preg_quote($node_one->getTitle()) . '.+' . preg_quote($node_two->getTitle()) . '/s';
-    $this->verbose($pattern);
-    $this->assertPattern($pattern, 'Most recently commented on node appears at the top of tracker');
+    return $node;
   }
 
   /**
@@ -353,14 +218,6 @@ public function testTrackerCronIndexing() {
       $nodes[$i] = $this->drupalCreateNode($edits[$i]);
     }
 
-    // Add a comment to the last node as other user.
-    $this->drupalLogin($this->otherUser);
-    $comment = [
-      'subject[0][value]' => $this->randomMachineName(),
-      'comment_body[0][value]' => $this->randomMachineName(20),
-    ];
-    $this->drupalPostForm('comment/reply/node/' . $nodes[3]->id() . '/comment', $comment, t('Save'));
-
     // Start indexing backwards from node 3.
     \Drupal::state()->set('tracker.index_nid', 3);
 
@@ -421,28 +278,23 @@ public function testTrackerAdminUnpublish() {
   /**
    * Passes if the appropriate history metadata exists.
    *
-   * Verify the data-history-node-id, data-history-node-timestamp and
-   * data-history-node-last-comment-timestamp attributes, which are used by the
-   * drupal.tracker-history library to add the appropriate "new" and "updated"
-   * indicators, as well as the "x new" replies link to the tracker.
-   * We do this in JavaScript to prevent breaking the render cache.
+   * Verify the data-history-node-id, data-history-node-timestamp attribute,
+   * which is used by the drupal.tracker-history library to add the appropriate
+   * "new" and "updated" indicators, as well as the "x new" replies link to the
+   * tracker. We do this in JavaScript to prevent breaking the render cache.
    *
    * @param int $node_id
    *   A node ID, that must exist as a data-history-node-id attribute
    * @param int $node_timestamp
    *   A node timestamp, that must exist as a data-history-node-timestamp
    *   attribute.
-   * @param int $node_last_comment_timestamp
-   *   A node's last comment timestamp, that must exist as a
-   *   data-history-node-last-comment-timestamp attribute.
    * @param bool $library_is_present
    *   Whether the drupal.tracker-history library should be present or not.
    */
-  public function assertHistoryMetadata($node_id, $node_timestamp, $node_last_comment_timestamp, $library_is_present = TRUE) {
+  public function assertHistoryMetadata($node_id, $node_timestamp, $library_is_present = TRUE) {
     $settings = $this->getDrupalSettings();
     $this->assertIdentical($library_is_present, isset($settings['ajaxPageState']) && in_array('tracker/history', explode(',', $settings['ajaxPageState']['libraries'])), 'drupal.tracker-history library is present.');
     $this->assertIdentical(1, count($this->xpath('//table/tbody/tr/td[@data-history-node-id="' . $node_id . '" and @data-history-node-timestamp="' . $node_timestamp . '"]')), 'Tracker table cell contains the data-history-node-id and data-history-node-timestamp attributes for the node.');
-    $this->assertIdentical(1, count($this->xpath('//table/tbody/tr/td[@data-history-node-last-comment-timestamp="' . $node_last_comment_timestamp . '"]')), 'Tracker table cell contains the data-history-node-last-comment-timestamp attribute for the node.');
   }
 
 }
diff --git a/core/modules/tracker/tracker.info.yml b/core/modules/tracker/tracker.info.yml
index 79d179d..2a62162 100644
--- a/core/modules/tracker/tracker.info.yml
+++ b/core/modules/tracker/tracker.info.yml
@@ -3,7 +3,6 @@ type: module
 description: 'Enables tracking of recent content for users.'
 dependencies:
   - node
-  - comment
 package: Core
 version: VERSION
 core: 8.x
diff --git a/core/modules/tracker/tracker.module b/core/modules/tracker/tracker.module
index dbde704..d45c53d 100644
--- a/core/modules/tracker/tracker.module
+++ b/core/modules/tracker/tracker.module
@@ -93,26 +93,27 @@ function tracker_cron() {
       // Get unique user IDs via entityQueryAggregate because it's the easiest
       // database agnostic way. We don't actually care about the comments here
       // so don't add an aggregate field.
-      $result = \Drupal::entityQueryAggregate('comment')
-        ->condition('entity_type', 'node')
-        ->condition('entity_id', $node->id())
-        ->condition('uid', $node->getOwnerId(), '<>')
-        ->condition('status', CommentInterface::PUBLISHED)
-        ->groupBy('uid')
-        ->execute();
-      if ($result) {
-        $query = db_insert('tracker_user');
-        foreach ($result as $row) {
-          $query->fields([
-            'uid' => $row['uid'],
-            'nid' => $nid,
-            'published' => CommentInterface::PUBLISHED,
-            'changed' => $changed,
-          ]);
+      if (\Drupal::moduleHandler()->moduleExists('comment')) {
+        $result = \Drupal::entityQueryAggregate('comment')
+          ->condition('entity_type', 'node')
+          ->condition('entity_id', $node->id())
+          ->condition('uid', $node->getOwnerId(), '<>')
+          ->condition('status', CommentInterface::PUBLISHED)
+          ->groupBy('uid')
+          ->execute();
+        if ($result) {
+          $query = db_insert('tracker_user');
+          foreach ($result as $row) {
+            $query->fields([
+              'uid' => $row['uid'],
+              'nid' => $nid,
+              'published' => CommentInterface::PUBLISHED,
+              'changed' => $changed,
+            ]);
+          }
+          $query->execute();
         }
-        $query->execute();
       }
-
       // Note that we have indexed at least one node.
       $last_nid = $nid;
 
@@ -293,9 +294,11 @@ function _tracker_add($nid, $uid, $changed) {
  */
 function _tracker_calculate_changed($node) {
   $changed = $node->getChangedTime();
-  $latest_comment = \Drupal::service('comment.statistics')->read([$node], 'node', FALSE);
-  if ($latest_comment && $latest_comment->last_comment_timestamp > $changed) {
-    $changed = $latest_comment->last_comment_timestamp;
+  if (\Drupal::hasService('comment.statistics')) {
+    $latest_comment = \Drupal::service('comment.statistics')->read([$node], 'node', FALSE);
+    if ($latest_comment && $latest_comment->last_comment_timestamp > $changed) {
+      $changed = $latest_comment->last_comment_timestamp;
+    }
   }
   return $changed;
 }
diff --git a/core/modules/tracker/tracker.pages.inc b/core/modules/tracker/tracker.pages.inc
index 76a775f..4c40be5 100644
--- a/core/modules/tracker/tracker.pages.inc
+++ b/core/modules/tracker/tracker.pages.inc
@@ -48,32 +48,34 @@ function tracker_page($account = NULL) {
 
   $cache_tags = [];
   $rows = [];
+  $has_comment_stats_service = \Drupal::hasService('comment.statistics');
   if (!empty($tracker_data)) {
     // Load nodes into an array with the same order as $tracker_data.
     $nodes = Node::loadMultiple(array_keys($tracker_data));
 
     // Enrich the node data.
-    $result = \Drupal::service('comment.statistics')->read($nodes, 'node', FALSE);
-    foreach ($result as $statistics) {
-      // The node ID may not be unique; there can be multiple comment fields.
-      // Make comment_count the total of all comments.
-      $nid = $statistics->entity_id;
-      if (empty($nodes[$nid]->comment_count)
-          || !is_numeric($nodes[$nid]->comment_count)) {
-        $nodes[$nid]->comment_count = $statistics->comment_count;
-      }
-      else {
-        $nodes[$nid]->comment_count += $statistics->comment_count;
-      }
-      // Make the last comment timestamp reflect the latest comment.
-      if (!isset($nodes[$nid]->last_comment_timestamp)) {
-        $nodes[$nid]->last_comment_timestamp = $statistics->last_comment_timestamp;
-      }
-      else {
-        $nodes[$nid]->last_comment_timestamp = max($nodes[$nid]->last_comment_timestamp, $statistics->last_comment_timestamp);
+    if ($has_comment_stats_service) {
+      $result = \Drupal::service('comment.statistics')
+        ->read($nodes, 'node', FALSE);
+      foreach ($result as $statistics) {
+        // The node ID may not be unique; there can be multiple comment fields.
+        // Make comment_count the total of all comments.
+        $nid = $statistics->entity_id;
+        if (empty($nodes[$nid]->comment_count) || !is_numeric($nodes[$nid]->comment_count)) {
+          $nodes[$nid]->comment_count = $statistics->comment_count;
+        }
+        else {
+          $nodes[$nid]->comment_count += $statistics->comment_count;
+        }
+        // Make the last comment timestamp reflect the latest comment.
+        if (!isset($nodes[$nid]->last_comment_timestamp)) {
+          $nodes[$nid]->last_comment_timestamp = $statistics->last_comment_timestamp;
+        }
+        else {
+          $nodes[$nid]->last_comment_timestamp = max($nodes[$nid]->last_comment_timestamp, $statistics->last_comment_timestamp);
+        }
       }
     }
-
     // Display the data.
     foreach ($nodes as $node) {
       // Set the last activity time from tracker data. This also takes into
@@ -103,18 +105,19 @@ function tracker_page($account = NULL) {
             '#account' => $node->getOwner(),
           ],
         ],
-        'comments' => [
+      ];
+      if ($has_comment_stats_service) {
+        $row['comments'] = [
           'class' => ['comments'],
           'data' => $comments,
           'data-history-node-last-comment-timestamp' => $node->last_comment_timestamp,
-        ],
-        'last updated' => [
-          'data' => t('@time ago', [
-            '@time' => \Drupal::service('date.formatter')->formatTimeDiffSince($node->last_activity),
-          ]),
-        ],
+        ];
+      }
+      $row['last updated'] = [
+        'data' => t('@time ago', [
+          '@time' => \Drupal::service('date.formatter')->formatTimeDiffSince($node->last_activity),
+        ])
       ];
-
       $rows[] = $row;
 
       // Add node and node owner to cache tags.
@@ -130,7 +133,7 @@ function tracker_page($account = NULL) {
 
   $page['tracker'] = [
     '#rows' => $rows,
-    '#header' => [t('Type'), t('Title'), t('Author'), t('Comments'), t('Last updated')],
+    '#header' => $has_comment_stats_service ? [t('Type'), t('Title'), t('Author'), t('Comments'), t('Last updated')] : [t('Type'), t('Title'), t('Author'), t('Last updated')],
     '#type' => 'table',
     '#empty' => t('No content available.'),
   ];