Harmony Contract Verification Tutorial

Tutorial for harmony contract verification using hardhat-etherscan

Prerequisites

• Hardhat installed globally (https://hardhat.org/getting-started/)
• Install npx and npm version 16

To begin

• npm install
• npx hardhat compile
• create a .env file and add PRIVATE_KEY property, this is your well-funded ONE wallet which will be used to deploy the smart contracts
• npx hardhat run --network harmony scripts/deployContractTest.js

Record the output of the deployed smart contract address, this will be used for verification

Example:

Starting deploy
Deploying
Initially Deployed 0x4eBb2a1714384d54Dc287B9FbA1c8D4639717d43

Note this tutorial can be used to demonstrate the hardhat verify plugin as well as the Harmony Explorer multi-file upload. The contents of the contracts/ directory contain the individual files used to build the SimpleToken.sol contract. You can either verify manually in Harmony Explorer or use the modified hardhat-etherscan.

Verifying using hardhat-etherscan

The hardhat-etherscan module has been modified to support Harmony One. Please make sure that you include the correct package (see package.json).

To begin npx hardhat verify --network harmony 'deployed contract address'
e.g. npx hardhat verify --network harmony 0x4eBb2a1714384d54Dc287B9FbA1c8D4639717d43

If you see the following error, run the command with a more specific contract:

Error in plugin @nomiclabs/hardhat-etherscan: More than one contract was found to match the deployed bytecode.
Please use the contract parameter with one of the following contracts:
  * contracts/ERC20.sol:ERC20
  * contracts/SimpleToken.sol:SimpleToken

For example:

  hardhat verify --contract contracts/Example.sol:ExampleContract <other args>

If you are running the verify subtask from within Hardhat instead:

  await run("verify:verify", {
    <other args>,
    contract: "contracts/Example.sol:ExampleContract"
  };

Run again with the following command (to specify the exact contract)
npx hardhat verify --network harmony --contract contracts/SimpleToken.sol:SimpleToken 'deployed contract address'
e.g. npx hardhat verify --network harmony --contract contracts/SimpleToken.sol:SimpleToken 0x4eBb2a1714384d54Dc287B9FbA1c8D4639717d43

Result will look like the following (if successful)

Nothing to compile
Compiling 1 file with 0.6.2
Successfully submitted source code for contract
contracts/SimpleToken.sol:SimpleToken at 0x4eBb2a1714384d54Dc287B9FbA1c8D4639717d43
for verification on the block explorer. Waiting for verification result...

Successfully verified contract SimpleToken on Etherscan.
https://explorer.harmony.one/address/0x4eBb2a1714384d54Dc287B9FbA1c8D4639717d43#code

Here is an example of the deployed and verified smart contract: verified

Troubleshooting

I'll update this as more people face challenges when verifying contracts.

General Issues

Missing dist directory in hardhat-etherscan As we move to push a PR to hardhat, I had to remove the dist directory from hardhat. You can

Windows Users

Disable the longpathnames limit by following the instructions in this link

NOTE: For Devnet support

Step 1:

Edit node_modules/@nomiclabs/hardhat-etherscan/dist/src/ChainConfig.js add the following under harmonyTest:

    harmonyDev: {
        chainId: 1666900000,
        urls: {
            apiURL: "https://ctrver.b.hmny.io/verify?network=devnet",
            browserURL: "https://api.s0.ps.hmny.io",
        },
    },

Step 2:

In your hardhat.config.js file add the following:

    harmonyDev: {
      url: "https://api.s0.ps.hmny.io",
      accounts: [process.env.PRIVATE_KEY]
    }

Step 3:

In the same hardhat.config.js file add the following to your etherscan api key config (API key is not required, you can use any string):

  etherscan: {
    apiKey: {
      harmony: 'your API key',
      harmonyDev: 'your API key',
    }
  }