Bug: Response does not get mutated when Middleware returns early

[sdangol]

Expected Behavior

The Response in reqCtx.res should also get mutated when a middleware returns early when there are multiple middlewares. The middleware that would do the post processing should be able to access the response returned by the earlier middleware

Current Behavior

The Response in reqCtx.res doesn't get mutated and the post processing middleware can't access the response

Code snippet

This test fails currently as the response is not being mutated

it('allows post processing middleware to access the response returned early by a pre processing middleware', async () => {
  // Prepare
  const app = new Router();
  let message = "";
  app.get('/test', [
    async ({ reqCtx, next }) => {
      await next();
      const clonedRes = reqCtx.res.clone();
      message = (await clonedRes.json()).message;
    },
    () => {
      return Promise.resolve({ message: 'Middleware applied' })
    }
  ], () => {
    return { message: 'Handler applied' }
  });

  // Act
  await app.resolve(
    createTestEvent('/test', 'GET'),
    context
  );

  // Assess
  expect(message).toEqual('Middleware applied');
})

Steps to Reproduce

1. Run the above unit test in the project
2. The message is empty and hasn't been mutated

Possible Solution

Move the Response mutation logic in Router.ts to the composeMiddleware helper function

Powertools for AWS Lambda (TypeScript) version

latest

AWS Lambda function runtime

22.x

Packaging format used

npm

Execution logs

[powertools-for-aws-oss-automation]

Warning

This issue is now closed. Please be mindful that future comments are hard for our team to see.
If you need more assistance, please either reopen the issue, or open a new issue referencing this one.
If you wish to keep having a conversation with other community members under this issue feel free to do so.