What are some advanced examples of async assertions in Chai?

What are some advanced examples of async assertions in Chai?

Chai provides powerful async assertions that can be used with promises and async/await. For example, you can use chai-as-promised to assert that a promise resolves to a specific value.

Can you show me a code snippet for that?

Sure! Here's a simple example:

const chai = require('chai');
const chaiAsPromised = require('chai-as-promised');
chai.use(chaiAsPromised);

const myPromise = () => Promise.resolve(42);

describe('Async Assertion', () => {
  it('should resolve to 42', () => {
    return chai.expect(myPromise()).to.eventually.equal(42);
  });
});

What if I want to test for a rejection instead?

You can use the rejected assertion for that. Here's an example:

const myRejectedPromise = () => Promise.reject(new Error('Failure'));

describe('Async Rejection Assertion', () => {
  it('should be rejected with an error', () => {
    return chai.expect(myRejectedPromise()).to.be.rejectedWith('Failure');
  });
});