Contract calling contract question

Question

I wasn't able to get this working using the other "contracts from contracts" examples, so I thought I would post it here. There are two things going wrong:

1. The Sent Event in the first contract never emits anything.
2. The sendOrder method in the second contract never seems to execute.

Here is the sol file:

pragma solidity ^0.4.11;

contract TA2_Transfer {
    address public sender;
    address public receiver;
    uint public packageCount;
    mapping (address => uint) public balances;
    event Transfer(address from, address to, uint objCount);
    function sendToReceiver(address sender, address receiver, uint256 objCount) payable {
        if (balances[sender] < objCount) return;
        balances[sender] -= objCount;
        balances[receiver] += objCount;
        Transfer(sender, receiver, objCount);
    }
    function getBalance(address _sender) returns(uint) {
        return balances[_sender];
    }
}

contract ShippingOrder{
    TA2_Transfer public t;
    address public oOrigin;
    address public oShipper;
    address public oCarrier;
    address public oReceiver;
    uint public oCount;
    mapping (address => uint) public oBalances;
    event Sent(address shipper, address carrier, address receiver, uint objCount);
    function ShippingOrder() {
        oBalances[tx.origin] = 200;
    }
    function getBalance(address _sender) returns(uint) {
        return oBalances[_sender];
    }
    function sendOrder(address oOrigin, address oShipper, address oCarrier,  address oReceiver, uint256 oCount) payable{
        t.sendToReceiver(oOrigin, oShipper, oCount);
        t.sendToReceiver(oShipper, oCarrier, oCount);
        t.sendToReceiver(oCarrier, oReceiver, oCount);
    }
}

And here is the test file:

var ShippingOrder = artifacts.require("./ShippingOrder.sol");
contract('ShippingOrder', function(accounts) {
var meta;
var  xInt = 1;
var origin = accounts[0];
var shipper = accounts[1];
var carrier = accounts[2];
var receiver = accounts[3];
 it("should put 300 in the first account", function() {
    return ShippingOrder.deployed().then(function(instance) {
      return instance.getBalance.call(accounts[0]);
    }).then(function(balance) {
      assert.equal(balance.valueOf(), 200, "300 wasn't in the first account");
    });
  });
it("should transfer 1 package from Origin to Receiver", function() {
    return ShippingOrder.deployed().then(function(instance) {
      meta = instance;
      return meta.sendOrder.call(origin, shipper, carrier, receiver, xInt);
     }).then(function(balance) {
      return meta.getBalance.call(origin);
    }).then(function(balance) {
      origin_balance = balance.toNumber();
      return meta.getBalance.call(shipper);
    }).then(function(balance) {
      shipper_balance = balance.toNumber();
      return meta.getBalance.call(carrier);
    }).then(function(balance) {
      carrier_balance = balance.toNumber();
      return meta.getBalance.call(receiver);
    }).then(function(balance) {
      receiver_balance = balance.toNumber();
      assert.equal(origin_balance, 199, "Origin Balance Not 199");
      assert.equal(shipper_balance,0, "Shipper Balance Not 0");
      assert.equal(carrier_balance, 0, "Carrier Balance Not 0");
      assert.equal(receiver_balance, 1, "Receiver Balance Not 1");
    });
});
});

Any help would be greatly appreciated... it feels like I am close!!

Frank

Answer 1

Where you do t.sendToReceiver

You have t defined with TA2_Transfer public t;

That types it, reserves storage and sets up a public getter function. This missing piece is to set t to an actual instance of a TA2.

One possible approach:

You'll need TA2 deployed so you have an address to work with. Do that first. Then pass the address to ShippingOrder in the constructor:

function ShippingOrder(address TA2) {
  t = TA2_Transfer(TA2);
}

Important thing is type it and also set it to an instance.

Hope it helps.

UPDATE:

More details.

This line stops things from happening. I commented it out to avoid dealing with setting up the use-case for testing. Obviously, a condition that needs to be met for things to work: if (balances[sender] < objCount) return;

And, I added returns(bool success) to important functions and played with the events to make it seem more complete. Added missing Sent() and success checks in ShippingOrder().

I didn't spend any time considering how this maps to the use-case. Just addressing the issues raised. No warranty.

pragma solidity ^0.4.11;
contract TA2_Transfer {
    address public sender;
    address public receiver;
    uint public packageCount;

    mapping (address => uint) public balances;
    event Transfer(address from, address to, uint objCount);

    function sendToReceiver(address sender, address receiver, uint256 objCount) 
        payable 
        returns(bool success) 
    {
        // if (balances[sender] < objCount) return false;
        balances[sender] -= objCount;
        balances[receiver] += objCount;
        Transfer(sender, receiver, objCount);
        return true;
    }
    function getBalance(address _sender) returns(uint) {
        return balances[_sender];
    }
}
contract ShippingOrder{
    TA2_Transfer public t;
    address public oOrigin;
    address public oShipper;
    address public oCarrier;
    address public oReceiver;
    uint public oCount;

    mapping (address => uint) public oBalances;
    event Sent(address sender, address origin, address shipper, address carrier, address receiver, uint objCount);

    function ShippingOrder(address TA2) {
        t = TA2_Transfer(TA2);
        oBalances[msg.sender] = 200;
    }
    function getBalance(address _sender) returns(uint) {
        return oBalances[_sender];
    }
    function sendOrder(address oOrigin, address oShipper, address oCarrier,  address oReceiver, uint256 oCount) 
        payable 
        returns(bool success) 
    {
        if(!t.sendToReceiver(oOrigin, oShipper, oCount)) throw;
        if(!t.sendToReceiver(oShipper, oCarrier, oCount)) throw;
        if(!t.sendToReceiver(oCarrier, oReceiver, oCount)) throw;
        Sent(msg.sender, oOrigin, oShipper, oCarrier, oReceiver, oCount);
        return true;
    }
}

In Remix to show it working: