@nomiclabs/buidler/sample-project/test/sample-test.js

Buidler is an extensible developer tool that helps smart contract developers increase productivity by reliably bringing together the tools they want.

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

describe("Greeter", function() {
  it("Should return the new greeting once it's changed", async function() {
    const Greeter = await ethers.getContractFactory("Greeter");
    const greeter = await Greeter.deploy("Hello, world!");
    
    await greeter.deployed();
    expect(await greeter.greet()).to.equal("Hello, world!");

    await greeter.setGreeting("Hola, mundo!");
    expect(await greeter.greet()).to.equal("Hola, mundo!");
  });
});