How do you write and run tests in Hardhat?

Hardhat supports multiple testing frameworks. Using Mocha and Chai:

const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Token", function () {
  let token;
  let owner, addr1;

  beforeEach(async function () {
    [owner, addr1] = await ethers.getSigners();
    const Token = await ethers.getContractFactory("Token");
    token = await Token.deploy();
  });

  it("Should assign total supply to owner", async function () {
    const ownerBalance = await token.balanceOf(owner.address);
    expect(await token.totalSupply()).to.equal(ownerBalance);
  });
});

Run tests with: npx hardhat test