No results when executing MySQL query

I'm writing a simple db infrastructure. select function suppose to perform a simple query and returns a result set.

For some reason, I am not getting any results back.

What should I do in order to fix my code?

protected $connection;

public function connect() {    
        // Try and connect to the database
        if(!isset($this -> connection)) {
            // Load configuration as an array. Use the actual location of your configuration file
            $config = parse_ini_file('config.ini');
            $this -> connection = new mysqli('localhost',$config['username'],$config['password'],$config['dbname']);
        }

        // If connection was not successful, handle the error
        if($this -> connection === false) {
            // Handle error - notify administrator, log to a file, show an error screen, etc.                       
            return false;
        }

        return $this -> connection;
    }

public function select($query) {        
    $connection = $this -> connect();       
    $stmt = $connection->prepare($query);       
    $stmt->execute();
    $stmt->store_result();
    $result = $stmt->get_result();      
    $rows = array();

    if($result === false) {                 
        return false;
    }

    while ($row = $result -> fetch_assoc()) {                       
        $rows[] = $row;
    }

    $stmt->free_result();
    $stmt->close();
    $connection->next_result();
    return $rows;
}

Execution:

$result = $db -> select('SELECT 1');
echo $result;