public function testConstructor()
{
$s = new Shipping(new Fedex('KEY', 'PASSWORD', 'ACCT_NUM', 'METER_NUM'));
$this->assertInstanceOf('Pop\\Shipping\\Shipping', $s);
$this->assertInstanceOf('Pop\\Shipping\\Adapter\\Fedex', $s->adapter());
$s = new Shipping(new Ups('ACCESS_KEY', 'USER_ID', 'PASSWORD'));
$this->assertInstanceOf('Pop\\Shipping\\Shipping', $s);
$this->assertInstanceOf('Pop\\Shipping\\Adapter\\Ups', $s->adapter());
$s = new Shipping(new Usps('USERNAME', 'PASSWORD'));
$this->assertInstanceOf('Pop\\Shipping\\Shipping', $s);
$this->assertInstanceOf('Pop\\Shipping\\Adapter\\Usps', $s->adapter());
}