Sokil\Mongo\ExpressionTest::setUp PHP Method

    public function setUp()
    {
        // connect to mongo
        $client = new Client(getenv('PHPMONGO_DSN') ? getenv('PHPMONGO_DSN') : null);
        // select database
        $database = $client->getDatabase('test');
        // select collection
        $this->collection = $database->getCollection('phpmongo_test_collection');
    }