openzeppelin-contracts/test/sanity.test.js

const { ethers } = require('hardhat');
const { expect } = require('chai');
const { loadFixture, mine } = require('@nomicfoundation/hardhat-network-helpers');

async function fixture() {
  return {};
}

describe('Environment sanity', function () {
  beforeEach(async function () {
    Object.assign(this, await loadFixture(fixture));
  });

  describe('snapshot', function () {
    let blockNumberBefore;

    it('cache and mine', async function () {
      blockNumberBefore = await ethers.provider.getBlockNumber();
      await mine();
      expect(await ethers.provider.getBlockNumber()).to.equal(blockNumberBefore + 1);
    });

    it('check snapshot', async function () {
      expect(await ethers.provider.getBlockNumber()).to.equal(blockNumberBefore);
    });
  });
});