public function testHash()
 {
     // test_token|sale_id_1|optional|user defined|http://txn_completed|http://server_side_notification_url|INR|5.00
     // test_token|sale_id_1|optional|user defined|http://txn_completed|http://server_side_notification_url|INR|5.00
     $bill = new Bill();
     $bill->setAccessToken("test_token");
     $bill->setCommand("debit");
     $bill->setUniqueId("sale_id_1");
     $bill->setComments("optional");
     $bill->setUdf("user defined");
     $bill->setReturnUrl("http://txn_completed");
     $bill->setNotificationUrl("http://server_side_notification_url");
     $bill->setAmount("5.00");
     $bill->setCurrency("INR");
     $hash = $bill->getHash("merchant_salt");
     echo "Hash String [" . $bill . "]\n";
     if (0 != strcmp($hash, "7a97febb1ee0fd596936be066b1617ded7ac558248985a22f7dcc770ad399874f16ad5ff3e2168326582a96d68445ed297540b8a64affc36938a11e0cd1d64e7")) {
         echo "Hash Mismatch : " . $hash;
         throw new \Exception();
     } else {
         echo "Hash : " . $hash;
     }
 }