ClientRequest: Supports chunk/encoding in the "end" method

[kettanaito]

Changes

• Adds normalization for ClientRequest.end arguments.
• Appends a body chunk given to end() method to the existing request body.
• Propagates given body chunk to end() method to the original call of req.end() (when performing an original request).
• Merges options.headers and kOutHeaders when resolving requestHeaders present in the intercepted request object.
• Propagates kOutHeaders on the original request, if such headers were set.

GitHub

• Fixes ClientRequestOverride.end() does not accept chunk/encoding #32
• Fixes supertest along with msw for mocks msw#275

Roadmap

• Ensure the encoding is propagated
• Add an integration test covering the issue
• Ensure the request body written through req.write() is also written on the original request:

https://github.com/mswjs/node-request-interceptor/blob/94969084d99969fe8bfb7b684c9b9d298c007d4b/src/http/ClientRequest/ClientRequestOverride.ts#L243-L246

Per spec, it could be enough to just pass the entire request body as the first argument to the req.end() call of the original request.

• Property type annotate arguments in test for normalizeHttpRequestEndParams function (no any)
• Capture all headers (both initial options.headers and headers added via this.setHeader())

[kettanaito]

Headers set via ClientRequest.setHeader() are not captured

This is because the this.setHeader() method is not patched. At the moment only the options.headers are captured, so any request headers set after the request has been created are ignored. This is what supertest does when .send({ json: true }) (sending a JSON request body).