feat(event-handler): expose response streaming in public API

[svozza]

Summary

This PR adds streaming functionality to the public API. Streaming is now used like so:

import {Router, streamify} from '@aws-lambda-powertools/event-handler/experimental-rest';

const app = new Router();

app.get('/event', async ({event}) => {
  return Readable.from(Buffer.from(JSON.stringify(event)))
});

export const handler = streamify(app)

Changes

• Created streamify function that turns a Router instance into a handler that can return streaming responses.
• Create a fallback streamifyHandler function that is used when streamify is used in non-lambda environments, which is useful for unit tests.

Testing

• Moved the logic from parseStreamOutput used by the tests to the fallback streamifyHandler function.
• Updated all the unit tests to use the streamify function rather than app.resolveStream.
• Tested in a ambda with a streaming function URL set up.

Issue number: closes #4726

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Disclaimer: We value your time and bandwidth. As such, any pull requests created on non-triaged issues might not be successful.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud