ERC7984ERC20WrapperMock - Fhevm

Swapping from a non-confidential ERC-20 to a confidential ERC-7984 is simple and actually done within the ERC7984ERC20Wrapper. The wrapper operates in two steps:

Token transfer: The ERC-20 tokens are transferred in from the caller using SafeERC20.safeTransferFrom(), reverting automatically if unsuccessful.
Confidential minting: The contract mints equivalent ERC-7984 tokens to the recipient, which is guaranteed to succeed.

This example demonstrates how to deploy and test the wrapper using OpenZeppelin's smart contract library powered by ZAMA's FHEVM.

{% hint style="info" %} To run this example correctly, make sure the files are placed in the following directories:

.sol file → <your-project-root-dir>/contracts/
.ts file → <your-project-root-dir>/test/

This ensures Hardhat can compile and test your contracts as expected. {% endhint %}

{% tabs %}

{% tab title="ERC7984ERC20WrapperExample.sol" %}

solidity

// SPDX-License-Identifier: BSD-3-Clause-Clear
pragma solidity ^0.8.27;

import {ZamaEthereumConfig} from "@fhevm/solidity/config/ZamaConfig.sol";
import {IERC20} from "@openzeppelin/contracts/interfaces/IERC20.sol";
import {ERC7984ERC20Wrapper, ERC7984} from "@openzeppelin/confidential-contracts/token/ERC7984/extensions/ERC7984ERC20Wrapper.sol";

contract ERC7984ERC20WrapperExample is ERC7984ERC20Wrapper, ZamaEthereumConfig {
    constructor(
        IERC20 token,
        string memory name,
        string memory symbol,
        string memory uri
    ) ERC7984ERC20Wrapper(token) ERC7984(name, symbol, uri) {}
}

{% endtab %}

{% tab title="ERC7984Wrapper.test.ts" %}

typescript

import { expect } from 'chai';
import { ethers, fhevm } from 'hardhat';

describe('ERC7984ERC20WrapperExample', function () {
  let wrapper: any;
  let erc20: any;
  let owner: any;
  let user: any;

  const WRAP_AMOUNT = 1000;

  beforeEach(async function () {
    [owner, user] = await ethers.getSigners();

    // Deploy a mock ERC20 token (OZ ERC20Mock takes name, symbol, decimals)
    erc20 = await ethers.deployContract('ERC20Mock', ['Test ERC20', 'TERC', 18]);

    // Deploy the wrapper
    wrapper = await ethers.deployContract('ERC7984ERC20WrapperExample', [
      await erc20.getAddress(),
      'Confidential Token',
      'cTKN',
      'https://example.com/wrapped'
    ]);
  });

  describe('Initialization', function () {
    it('should set the correct name', async function () {
      expect(await wrapper.name()).to.equal('Confidential Token');
    });

    it('should set the correct symbol', async function () {
      expect(await wrapper.symbol()).to.equal('cTKN');
    });

    it('should reference the correct underlying token', async function () {
      expect(await wrapper.underlying()).to.equal(await erc20.getAddress());
    });
  });
});

{% endtab %}

{% endtabs %}