Error: Returned error: VM Exception while processing transaction: revert only owner can call this function

Question

I'm trying to test this contract using "truffle test" but it show the following error:

Error: Returned error: VM Exception while processing transaction: revert only owner can call this function - - Reason given: Only owner can call this function.

Gaming.sol

pragma solidity ^0.5.0;

contract Gaming {
    /* Our Online gaming contract */
    address public owner;
    bool public online;

    struct Player {
        uint wins;
        uint losses;
    }

    mapping (address => Player) public players;

    constructor() public payable {
        owner = msg.sender;
        online = true;
    }

    modifier isOwner() {
        require(msg.sender == owner, "Only owner can call this function");
        _;
    }

}

TestGaming.sol

pragma solidity ^0.5.0;

import "truffle/Assert.sol";
import "truffle/DeployedAddresses.sol";
import "../contracts/Gaming.sol";

contract TestGaming {
    uint public initialBalance = 10 ether;
    Gaming gaming;
    address owner;

    function beforeAll() public {
        gaming = Gaming(DeployedAddresses.Gaming());
        owner = gaming.owner();

    }

    function testWithdrawFunds() public {
        uint ownerBalanceBefore = owner.balance;
        gaming.withdrawFunds();
        uint ownerBalanceAfter = owner.balance;

        Assert.equal (initialBalance, ownerBalanceAfter - ownerBalanceBefore, "The owner's balance should have increased by 10 ether");
}

Error

Error: Returned error: VM Exception while processing transaction: revert only owner can call this function - - Reason given: Only owner can call this function.

Answer 1

You may deployed the Contract with other account and test it with another accounts..

please do add your test script