feat: use internal body if available for returning the response in its original form as much as possible

[usualoma]

Fixes #144

Reuse the following implementation idea to get the body inside the nodejs Response object and use it to return a response if available.

node-server/src/utils.ts

Lines 13 to 24 in a8117ce

	export function getResponseInternalBody(response: Response) {
	if (!kState || !response || !response.body) return
	const state = (response as any)[kState]
	if (!state || !state.body) return
	return state.body as {
	source: string | Uint8Array | FormData | Blob | null
	stream: ReadableStream
	length: number | null
	}
	}

[usualoma]

@yusukebe Would you please review?

[usualoma]

By the way, the following code is still used.

node-server/src/listener.ts

Lines 96 to 130 in a25fa2a

	/**
	* If content-encoding is set, we assume that the response should be not decoded.
	* Else if transfer-encoding is set, we assume that the response should be streamed.
	* Else if content-length is set, we assume that the response content has been taken care of.
	* Else if x-accel-buffering is set to no, we assume that the response should be streamed.
	* Else if content-type is not application/json nor text/* but can be text/event-stream,
	* we assume that the response should be streamed.
	*/
	const {
	'transfer-encoding': transferEncoding,
	'content-encoding': contentEncoding,
	'content-length': contentLength,
	'x-accel-buffering': accelBuffering,
	'content-type': contentType,
	} = resHeaderRecord
	if (
	transferEncoding ||
	contentEncoding ||
	contentLength ||
	// nginx buffering variant
	(accelBuffering && regBuffer.test(accelBuffering as string)) ||
	!regContentType.test(contentType as string)
	) {
	outgoing.writeHead(res.status, resHeaderRecord)
	await writeFromReadableStream(res.body, outgoing)
	} else {
	const buffer = await res.arrayBuffer()
	resHeaderRecord['content-length'] = buffer.byteLength
	outgoing.writeHead(res.status, resHeaderRecord)
	outgoing.end(new Uint8Array(buffer))
	}

Removing this will cause the following tests to fail

node-server/test/server.test.ts

Lines 78 to 83 in a25fa2a

	it('Should return 200 response - GET /ponyfill', async () => {
	const res = await request(server).get('/ponyfill')
	expect(res.status).toBe(200)
	expect(res.headers['content-type']).toMatch('text/plain')
	expect(res.text).toBe('Pony')
	})

[yusukebe]

Great! Looks good to me!