<?php
 namespace MongoDB\Tests\Operation;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Tests\FunctionalTestCase as BaseFunctionalTestCase;
 use Symfony\Bridge\PhpUnit\SetUpTearDownTrait;
 abstract class FunctionalTestCase extends BaseFunctionalTestCase {
 use SetUpTearDownTrait;
 private function doSetUp() {
 parent::setUp();
 $this->dropCollection();
 }
 private function doTearDown() {
 if ($this->hasFailed()) {
 return;
 }
 $this->dropCollection();
 }
 protected function createDefaultReadConcern() {
 return new ReadConcern();
 }
 protected function createDefaultWriteConcern() {
 return new WriteConcern(-2);
 }
 protected function createSession() {
 return $this->manager->startSession();
 }
 }
 