core/modules/tracker/src/Tests/TrackerTest.php | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/core/modules/tracker/src/Tests/TrackerTest.php b/core/modules/tracker/src/Tests/TrackerTest.php
index 72d691c..b09a8f6 100644
--- a/core/modules/tracker/src/Tests/TrackerTest.php
+++ b/core/modules/tracker/src/Tests/TrackerTest.php
@@ -185,7 +185,7 @@ function testTrackerHistoryMetadata() {
     );
     $node = $this->drupalCreateNode($edit);
 
-    // Verify.
+    // Verify that the history metadata is present.
     $this->drupalGet('activity');
     $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
     $this->drupalGet('activity/' . $this->user->id());
@@ -193,7 +193,9 @@ function testTrackerHistoryMetadata() {
     $this->drupalGet('user/' . $this->user->id() . '/activity');
     $this->assertHistoryMetadata($node->id(), $node->getChangedTime(), $node->getChangedTime());
 
-    // Add a comment to the page, make sure it is created after the node.
+    // 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 = array(
       'subject[0][value]' => $this->randomMachineName(),
       'comment_body[0][value]' => $this->randomMachineName(20),
@@ -205,7 +207,7 @@ function testTrackerHistoryMetadata() {
     // posted comment.
     $node = Node::load($node->id());
 
-    // Verify.
+    // 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());