diff --git a/tests/phpunit/includes/class-hierarchical-sort-test.php b/tests/phpunit/includes/class-hierarchical-sort-test.php
index 6be9e5d6c921d..a0d17c9035c20 100644
--- a/tests/phpunit/includes/class-hierarchical-sort-test.php
+++ b/tests/phpunit/includes/class-hierarchical-sort-test.php
@@ -67,8 +67,7 @@ public function test_return_all_post_ids() {
 			),
 		);
 
-		$hs     = Hierarchical_Sort::get_instance();
-		$result = $hs->sort( $input );
+		$result = Hierarchical_Sort::run( $input );
 		$this->assertEquals( array( 12, 3, 6, 5, 4, 7, 8, 9, 11, 10 ), $result['post_ids'] );
 		$this->assertEquals(
 			array(
@@ -112,8 +111,7 @@ public function test_return_orphans() {
 			),
 		);
 
-		$hs     = Hierarchical_Sort::get_instance();
-		$result = $hs->sort( $input );
+		$result = Hierarchical_Sort::run( $input );
 		$this->assertEquals( array( 11, 4, 7 ), $result['post_ids'] );
 		$this->assertEquals(
 			array(
@@ -185,8 +183,7 @@ public function test_post_with_empty_post_parent_are_considered_top_level() {
 			),
 		);
 
-		$hs     = Hierarchical_Sort::get_instance();
-		$result = $hs->sort( $input );
+		$result = Hierarchical_Sort::run( $input );
 		$this->assertEquals( array( 2, 3, 5, 6, 4, 7, 8, 9, 11, 10 ), $result['post_ids'] );
 		$this->assertEquals(
 			array(