My contract has a function that allows only the contract owner to add another address to a mapping.

How do I obtain the address of the contract owner that deployed the smart contract, and another address in order to test this function? I am able to write the javascript test for this, but can't figure out how to do so in solidity.

  • how do you test yr code? truffle?
    – Badr Bellaj
    Commented Jul 22, 2018 at 8:25
  • yes i am using truffle
    – tserg
    Commented Jul 22, 2018 at 8:48

2 Answers 2


by default in truffle/ganache the deployer is account[0] where accounts is the first parameter in the contract test function :

contract('MyContract', function(accounts) {
    address owner;
    address user;

    beforeEach(function() {
        owner = accounts[0];
        user = accounts[1];

in solidity if you're testing using a contract you can only test with the address of this later which is also the deployer.

NB: Depending on your code you don't have to read the "deployer" address in your constructor only to perform your test.

  • I find this answer a bit misleading since the author is asking explicitly for Solidity tests and not for the Javascript ones. I see that you clarify it in the second paragraph though. Commented Mar 7, 2021 at 17:41

You save it when the contract is created, for example:

pragma solidity ^0.4.24;

contract Ownable {
    address public owner;
    constructor() public {
        owner = msg.sender;
    modifier onlyOwner() {
        require(msg.sender == owner);

pragma solidity ^0.4.24;
import "./Ownable.sol";

contract MyContract is Ownable {
    mapping (address => bool) public wallets;
    function addWallet(address wallet) external onlyOwner {
        wallets[wallet] = true;

Here is a Truffle test example:

contract("MyContractUnitTest", function(accounts) {
    let myContract;

    let owner    = accounts[0];
    let nonOwner = accounts[1];
    let wallet   = accounts[2];

    describe("test:", function() {
        before(async function() {
            myContract = await artifacts.require("MyContract.sol").new();
        it("function addWallet should complete successfully if called by an owner", async function() {
            await myContract.addWallet(wallet, {from: owner});
        it("function addWallet should abort with an error if called by a non-owner", async function() {
            await tryCatch(myContract.addWallet(wallet, {from: nonOwner}), errTypes.revert);

    async function tryCatch(promise, errType) {
        try {
            await promise;
            throw null;
        catch (error) {
            assert(error, "Expected an error but did not get one");
            assert(error.message.startsWith(PREFIX + errType), "Expected an error starting with '" + PREFIX + errType + "' but got '" + error.message + "' instead");

    let errTypes = {
        revert            : "revert",
        outOfGas          : "out of gas",
        invalidJump       : "invalid JUMP",
        invalidOpcode     : "invalid opcode",
        stackOverflow     : "stack overflow",
        stackUnderflow    : "stack underflow",
        staticStateChange : "static state change"

    let PREFIX = "VM Exception while processing transaction: ";
  • And don't forget to start your test provider (Ganache, I would guess) with at least 3 accounts. Commented Jul 22, 2018 at 8:37
  • what is the equivalent of this in solidity? let owner = accounts[0]; let nonOwner = accounts[1]; let wallet = accounts[2];
    – tserg
    Commented Jul 22, 2018 at 8:51
  • @tserg: there is no equivalence (nor there should be any). Commented Jul 22, 2018 at 10:16
  • thanks for the clarification! i was inclined to think so as i have been unable to find anything on it.
    – tserg
    Commented Jul 22, 2018 at 11:02

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