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

A no dependency on anything but Mocha example.

Throw a known error, catch all errors, and only rethrow the known one.

  it('should throw an error', async () => {
    try {
      await myFunction()
      throw new Error('Expected error')
    } catch (e) {
      if (e.message && e.message === 'Expected error') throw e
    }
  })

If you test for errors often, wrap the code in a custom it function.

function itThrows(message, handler) {
  it(message, async () => {
    try {
      await handler()
      throw new Error('Expected error')
    } catch (e) {
      if (e.message && e.message === 'Expected error') throw e
    }
  })
}

Then use it like this:

  itThrows('should throw an error', async () => {
    await myFunction()
  })