In Hardhat tests, how to instantiate Contract with impersonated signer in Typescript?

Question

First, I'm sort of new to hardhat testing. I'm testing on a forked network and want to try to impersonate an account with an ERC20 token. Here is my code:

import { ethers } from "hardhat";
import { loadFixture } from "@nomicfoundation/hardhat-toolbox/network-helpers";
import { assert } from "chai";
import myContractArtifact from "../artifacts/contracts/MyContract.sol/myContractArtifact.json";

describe("MyContract", function () {
  async function deployContractAndSetVariables() {
    const [owner] = await ethers.getSigners();
    const impersonatedSigner = await ethers.getImpersonatedSigner(<addressOfImpersonatedAccount>);

    const contract = await ethers.deployContract("MyContract", [<constructorArgs>]);
    const myContract = await ethers.getContractAtFromArtifact(myContractArtifact, contract.target.toString(), impersonatedSigner);

    return { myContract, owner, impersonatedSigner };
  }

  it("Should...", async function () {
    const { myContract, owner } = await loadFixture(deployContractAndSetVariables);
    // tests
  });
});

I'm using a function I never see in examples - "ethers.getContractAtFromArtifact". Is this the best way to instantiate a contract using a impersonated signer?

I think ethers allows you to change Signer with myContract.connect(<newSigner>), but this creates Typescript errors. If you instantiate contract using standard method (new ethers.Contract(abi, address, <newSigner>)), you require the ABI, which you cannot import from the artifacts folder in Typescript (instead, you need to copy the json to a .ts file and export, which is a road I don't want to go down).

So is "getContractAtFromArtifact" the best way? I just haven't seen it in any examples.

Answer 1

You’ve to deploy the contract using the corresponding contract factory instance, that you can fetch using getContractFactory. Then, you can use .connect on the deployed contract instance, like:

const myContract_Factory = await ethers.getContractFactory("MyContract");
const myContract = await myContract_Factory.deploy([<constructorArgs>]);
await myContract.connect(impersonatedSigner).contractFunction([<functionArgs>]);

For better understanding, you can refer to this example.