assertNoParentLink example

// Post comment #1.     $this->drupalLogin($this->webUser);
    $subject_text = $this->randomMachineName();
    $comment_text = $this->randomMachineName();

    $comment1 = $this->postComment($this->node, $comment_text, $subject_text, TRUE);
    // Confirm that the comment was created and has the correct threading.     $this->assertTrue($this->commentExists($comment1), 'Comment #1. Comment found.');
    $this->assertEquals('01/', $comment1->getThread());
    // Confirm that there is no reference to a parent comment.     $this->assertNoParentLink($comment1->id());

    // Post comment #2 following the comment #1 to test if it correctly jumps     // out the indentation in case there is a thread above.     $subject_text = $this->randomMachineName();
    $comment_text = $this->randomMachineName();
    $this->postComment($this->node, $comment_text, $subject_text, TRUE);

    // Reply to comment #1 creating comment #1_3.     $this->drupalGet('comment/reply/node/' . $this->node->id() . '/comment/' . $comment1->id());
    $comment1_3 = $this->postComment(NULL, $this->randomMachineName(), '', TRUE);