Verify that an exception is thrown using Mocha / Chai and async/await

Question

I\'m struggling to work out the best way to verify that a promise is rejected in a Mocha test while using async/await.

Here\'s an example that works, but I dislike t

Answer 1

If test your Promised function, in the test must wrap the code inside a try/catch and the expect() must be inside the catch error block

const loserFunc = function(...args) {
  return new Promise((resolve, rejected) => {
    // some code
    return rejected('fail because...');
  });
};

So, then in your test

it('it should failt to loserFunc', async function() {
  try {
    await loserFunc(param1, param2, ...);
  } catch(e) {
    expect(e).to.be.a('string');
    expect(e).to.be.equals('fail because...');
  }
});

That is my approach, don't know a better way.