fix(ClientRequest): ignore message body for responses without body

src/interceptors/ClientRequest/utils/createResponse.test.ts

@@ -2,6 +2,7 @@ import { it, expect } from 'vitest'
 import { Socket } from 'net'
 import * as http from 'http'
 import { createResponse } from './createResponse'
+import { responseStatusCodesWithoutBody } from '../../../utils/responseUtils'
 
 it('creates a fetch api response from http incoming message', async () => {
   const message = new http.IncomingMessage(new Socket())
@@ -20,3 +21,25 @@ it('creates a fetch api response from http incoming message', async () => {
   expect(response.headers.get('content-type')).toBe('application/json')
   expect(await response.json()).toEqual({ firstName: 'John' })
 })
+
+it.each(responseStatusCodesWithoutBody)(
+  'ignores message body for %i response status',
+  (responseStatus) => {
+    const message = new http.IncomingMessage(new Socket())
+    message.statusCode = responseStatus
+
+    const response = createResponse(message)
+
+    // These chunks will be ignored: this response
+    // cannot have body. We don't forward this error to
+    // the consumer because it's us who converts the
+    // internal stream to a Fetch API Response instance.
+    // Consumers will rely on the Response API when constructing
+    // mocked responses.
+    message.emit('data', Buffer.from('hello'))
+    message.emit('end')
+
+    expect(response.status).toBe(responseStatus)
+    expect(response.body).toBe(null)
+  }
+)

src/interceptors/ClientRequest/utils/createResponse.ts

@@ -1,24 +1,29 @@
 import type { IncomingHttpHeaders, IncomingMessage } from 'http'
+import { responseStatusCodesWithoutBody } from '../../../utils/responseUtils'
 
 /**
  * Creates a Fetch API `Response` instance from the given
  * `http.IncomingMessage` instance.
  */
 export function createResponse(message: IncomingMessage): Response {
-  const readable = new ReadableStream({
-    start(controller) {
-      message.on('data', (chunk) => controller.enqueue(chunk))
-      message.on('end', () => controller.close())
-
-      /**
-       * @todo Should also listen to the "error" on the message
-       * and forward it to the controller. Otherwise the stream
-       * will pend indefinitely.
-       */
-    },
-  })
+  const responseBodyOrNull = responseStatusCodesWithoutBody.includes(
+    message.statusCode || 200
+  )
+    ? null
+    : new ReadableStream({
+        start(controller) {
+          message.on('data', (chunk) => controller.enqueue(chunk))
+          message.on('end', () => controller.close())
+
+          /**
+           * @todo Should also listen to the "error" on the message
+           * and forward it to the controller. Otherwise the stream
+           * will pend indefinitely.
+           */
+        },
+      })
 
-  return new Response(readable, {
+  return new Response(responseBodyOrNull, {
     status: message.statusCode,
     statusText: message.statusMessage,
     headers: createHeadersFromIncomingHttpHeaders(message.headers),

src/interceptors/XMLHttpRequest/utils/createResponse.ts

@@ -1,4 +1,4 @@
-const statusCodesWithoutBody = [204, 205, 304]
+import { responseStatusCodesWithoutBody } from '../../../utils/responseUtils'
 
 /**
  * Creates a Fetch API `Response` instance from the given
@@ -16,7 +16,9 @@ export function createResponse(
    * when constructing a Response instance.
    * @see https://github.com/mswjs/interceptors/issues/379
    */
-  const responseBodyOrNull = statusCodesWithoutBody.includes(request.status)
+  const responseBodyOrNull = responseStatusCodesWithoutBody.includes(
+    request.status
+  )
     ? null
     : body
 

src/utils/responseUtils.ts

@@ -0,0 +1,5 @@
+/**
+ * Response status codes for responses that cannot have body.
+ * @see https://fetch.spec.whatwg.org/#statuses
+ */
+export const responseStatusCodesWithoutBody = [204, 205, 304]

test/features/events/response.test.ts

@@ -198,7 +198,7 @@ it('XMLHttpRequest: emits the "response" event upon the original response', asyn
    * passthrough to the ClientRequest, it will perform an "OPTIONS" request first,
    * thus two request/response events emitted.
    */
-  expect(responseListener).toHaveBeenCalledTimes(1)
+  expect(responseListener).toHaveBeenCalledTimes(2)
 
   // Lookup the correct response listener call.
   const [{ response, request, isMockedResponse }] =