web3js – How to Sign Messages in Truffle Tests for Blockchain Applications

signaturetruffletruffle-testweb3js

I use Truffle to develop locally and run tests with truffle test (letting it create a temporary local blockchain).

In one of my tests I need to sign a message and for that I need the test wallet's privateKey. Unfortunately Truffle's contract() provides only an array of accounts (an array of addresses). I googled and it seems that there is no way to get the private key for those addresses.

So I tried the following:

await web3.eth.accounts.wallet.create(1);
const wallet = web3.eth.accounts.wallet[0];

// ok
const signedMessage = await wallet.sign('message');

// 🆘 fails with "sender account not recognized"
const contract = await MyContract.new({ from: wallet.address });

The Issue: The message signer should also be the deployer of the contract but when I try to instantiate the contract as the newly created wallet.address I get the following error:

1) Contract: MyContract
       test case no. 1 :
     Error: Returned error: sender account not recognized
      at Context.<anonymous> (test/my_contract.js:67:43)
      at processTicksAndRejections (node:internal/process/task_queues:96:5)

Best Answer

We observe that web3 exposes a few wallet functionalities that may not be very clear at first:

web3.eth.accounts / getAccounts()
web3.eth.accounts.wallet

It seems web3.eth.accounts.wallet.create is a utility meant to create accounts on the fly without actually auto-binding them to your local node's account list (credits: previous answer). You could use web3.eth.personal.newAccout() but that still wouldn't give you access to the private key.

Solution

Using the two utilities, we can (1) create a new wallet (2) add it to the "personal" list.

 /** Connect to ganache */
 const web3 = new Web3('http://localhost:7545')

 /** Create the new wallet */
 await web3.eth.accounts.wallet.create(1)
 const wallet = web3.eth.accounts.wallet[0]

 /** Bind the new wallet to the personal accounts */
 await web3.eth.personal.importRawKey(wallet.privateKey, '') // password is empty
 await web3.eth.personal.unlockAccount(wallet.address, '', 10000) // arbitrary duration

 /** Check wallet was added to accounts */
 const accounts = await web3.eth.getAccounts()
 console.log(accounts, wallet.address)

Small caveat here is that if you wanna pursue your contract creation, you also need to fund the new account with some ETH for gas.

Related Solutions

Truffle Testing – How to Return a Mapping in Truffle Test

You cannot return a mapping type. Among the several reasons: keys are never stored and cannot be retrieved. A mapping doesn't known if a key has data or not, and it should return the whole structure which is 2^256 addresses containing 32 bytes each.

If your contract has declared

mapping(address => uint[29]) public balanceOf;

The solidity compiler will create a getter with a single parameter that will accept an address.

var balance = await instance.balanceOf.call(account);
console.log(balance);

Truffle Deployment – What Address Deploys a Contract in Truffle Test

I think your problem appear because ceoAddress is not initialized properly, and it will have the value of 0x0000000000000000000000000000000000000000.

Now to change it the contract requires msg.sender == ceoAddress, this implies that msg.sender should be 0x0000000000000000000000000000000000000000. This operation can't be done because you do not have the private key that generates such address.

One options is to initialize your variable in the constructor with the sender account

contract AccessControl {

    address public ceoAddress;

    modifier onlyCEO() {
        require(msg.sender == ceoAddress);
        _;
    }

    constructor() {
        // ---- Initialize ceoAddress ----
        ceoAddress = msg.sender;
    }

    function setCEO(address _newCEO) external onlyCEO {
        require(_newCEO != address(0));

        ceoAddress = _newCEO;
    }
}

Truffle uses the first address returned by eth.accounts to deploy contracts.

2_deploy_contracts.js

module.exports = function(deployer, network, accounts) {
    // You can pass other parameters like gas or change the from
    deployer.deploy(AccessControl, { from: accounts[2] });
}

Check Truffle documentation for more options to use.

Best Answer

Related Solutions

Truffle Testing – How to Return a Mapping in Truffle Test

Truffle Deployment – What Address Deploys a Contract in Truffle Test

2_deploy_contracts.js

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