Example for asserting `HttpsError` thrown by cloud function

It would be really nice to have an example how to assert `HttpsError`, which are thrown by a cloud function.
```ts
exports.testCallable = functions.https.onCall((data, context) => {
console.log('testCallable');
return new functions.https.HttpsError('ok', 'this is an error');
})
```

How to write a test, that a `HttpsError` with the message `this is an error` was thrown?