wp/tests/phpunit/tests/comment.php

<?php

/**
 * @group comment
 */
class Tests_Comment extends WP_UnitTestCase {
	function test_wp_update_comment() {
		$post = $this->factory->post->create_and_get( array( 'post_title' => 'some-post', 'post_type' => 'post' ) );
		$comments = $this->factory->comment->create_post_comments( $post->ID, 5 );
		$result = wp_update_comment( array( 'comment_ID' => $comments[0], 'comment_parent' => $comments[1] ) );
		$this->assertEquals( 1, $result );
		$comment = get_comment( $comments[0] );
		$this->assertEquals( $comments[1], $comment->comment_parent );
		$result = wp_update_comment( array( 'comment_ID' => $comments[0], 'comment_parent' => $comments[1] ) );
		$this->assertEquals( 0, $result );
	}
}