How to access mapping array and address of contract in truffle test

Question

I have 3 contracts: sender, receiver and transferTest. I am getting error in transferTest due to an address array declared in the reciver contract:

receiver.sol:

pragma solidity ^0.5.8;

contract receiver{
   address public owner;
   mapping(address => uint) balance; 
constructor () public{
   owner = msg.sender;
}
function() external payable{
   balance[owner] += msg.value;}
}

transferTest:

pragma solidity ^0.5.8;
import "truffle/Assert.sol";
import "../contracts/sender.sol";
import "../contracts/receiver.sol";

contract TestTransfer{

   function testTransfer() public{
      sender senderObj = new sender();
      receiver receiverObj = new receiver();
      senderObj.transferTo(msg.sender, 10);
      Assert.equal(receiver.balance[receiver.owner], 9, "Received amount is not correct");
   }
}

I am getting following error message:

testingTransfer.sol:12:20: TypeError: Member "balance" not found or not visible after argument-dependent lookup in type(contract receiver). Assert.equal(receiver.balance[receiver.owner], 9, "Received amount is not correct"); ^--------------^

Compilation failed. See above. Truffle v5.1.67 (core: 5.1.67) Node v10.23.3

Also I used msg.sender for the address of receiver contract as the first argument of transferTo function. Please guide me how to replace msg.sender with the address of receiver contract. ==Update:Dec11 2021 My question is similar to: Accessing Solidity Mapping

Zulfi.

Answer 1

The balancew isn't public so it can't be accessed from the outside

mapping(address => uint) balance; 

If it were public you would be able to access like a function with the keys as parameters.

mapping(address => mapping(address => uint256)) public allowance; 

From truffle's console

> let allow = await token.allowance("0x1234..", "0x4444...")

---

A fixed version of TestTransfer should look like

contract TestTransfer {

   function testTransfer() public{
      sender senderObj = new sender();
      receiver receiverObj = new receiver();
      senderObj.transferTo(msg.sender, 10);
      Assert.equal(receiverObj.balance(receiverObj.owner()), 9, "Received amount is not correct");
   }
}