How to read a variables in deployed contract via cast command?

Question

contract testContract {
   address private test1;
   string publictest2;
  }

How do I use foundry framework test cases to read the storage slots? https://book.getfoundry.sh/cheatcodes/load

// This does not work for me
    function test() public {
        vm.startPrank(address(1));

        bytes slot_0= vm.load(address(testContract), bytes32(uint256(0)));
        emit log_address((slot_0)); 
    }
}

Answer 1

vm.load returns bytes32 and not bytes memory. If you want convert bytes32 to address and log it to the console then you should write:

emit log_address(address(uint160(uint256(slot_0))));

And here is an example test:

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.10;

import "forge-std/Test.sol";

contract ContractTest is Test {
    TestContract contractT;

    function testAddress() public {
        // Deploy contract
        contractT = new TestContract();

        bytes32 slot_0 = vm.load(address(contractT), bytes32(uint256(0)));
        // Following line will emit address which deployed TestContract instance
        emit log_address(address(uint160(uint256(slot_0))));
    }
}

contract TestContract {
    address private test1;
    string publictest2;

    constructor() {
        test1 = msg.sender;
    }
}