How it works

First, copy the contracts/Voting.sol code in Remix IDE and deploy it.

Then, you'll be able to call the addVoter function with your deploying address.

Once you added multiple voters, you need to call the startProposalRegistration function which will end the addVoter session and allow you to add proposals with the addProposal function. Only whitelisted addresses can add proposals. If the owner has not been whitelisted, he won't be able to participate.

Once you added multiple proposals, you need to call the endProposalRegistration function to end this session. Then, start the voting session by calling startVotingSession function. Voters will be able to vote using the vote method.

To end the voting session, call the endVotingSession function. Finally, the owner must call the tallyVotes method. Everyone will then be able to call the getWinner function and retrieve the winning proposal.

Tests

To run tests, first install packages :

$ npm install

Then, run tests using truffle :

$ truffle test test/voting.test.js --network development

Notes

I started using the Ownable.sol contract from OpenZeppelin but then I switched to AccessControl.sol which is a more advanced contract to deal with access control. This is useful to handle multiple roles (DEFAULT_ADMIN_ROLE and VOTER_ROLE here).

If there are 2 winning proposals (max + same vote count) then the first one will be chosen. This may not be the behaviour we want. One possible solution would be to prevent ending the vote session if this case happen. An other solution would be to allow the owner openning the vote session again if the case happen in the tallyVotes function.