public function testRecurByDate()
 {
     $this->specify('sets the recurring fields', function () {
         $i = new \CoinSimple\Invoice();
         verify($i->data())->equals(array());
         $i->recurByDate(4);
         $data = $i->data();
         verify(array_key_exists('invoice_type', $data))->true();
         verify(array_key_exists('interval', $data))->true();
         verify($data['invoice_type'])->equals("date");
         verify($data['interval'])->equals(4);
     });
     $this->specify('converts param to int', function () {
         $i = new \CoinSimple\Invoice();
         verify($i->data())->equals(array());
         $i->recurByDate("4");
         $data = $i->data();
         verify(array_key_exists('invoice_type', $data))->true();
         verify(array_key_exists('interval', $data))->true();
         verify($data['invoice_type'])->equals("date");
         verify($data['interval'])->equals(4);
     });
 }