fix(fetch): allow custom implementation of AbortSignal (#1608)

lib/fetch/request.js

@@ -835,10 +835,6 @@ webidl.converters.RequestInfo = function (V) {
   return webidl.converters.USVString(V)
 }
 
-webidl.converters.AbortSignal = webidl.interfaceConverter(
-  AbortSignal
-)
-
 // https://fetch.spec.whatwg.org/#requestinit
 webidl.converters.RequestInit = webidl.dictionaryConverter([
   {
@@ -913,9 +909,7 @@ webidl.converters.RequestInit = webidl.dictionaryConverter([
   },
   {
     key: 'signal',
-    converter: webidl.nullableConverter(
-      webidl.converters.AbortSignal
-    )
+    converter: webidl.converters.any
   },
   {
     key: 'window',

test/fetch/abort.js

@@ -7,6 +7,8 @@ const { once } = require('events')
 const { ReadableStream } = require('stream/web')
 const { DOMException } = require('../../lib/fetch/constants')
 
+const { AbortController: NPMAbortController } = require('abort-controller')
+
 /* global AbortController */
 
 test('parallel fetch with the same AbortController works as expected', async (t) => {
@@ -106,3 +108,31 @@ test('Readable stream synchronously cancels with AbortError if aborted before re
 
   t.end()
 })
+
+test('Allow the usage of custom implementation of AbortController', async (t) => {
+  const body = {
+    fixes: 1605
+  }
+
+  const server = createServer((req, res) => {
+    res.statusCode = 200
+    res.end(JSON.stringify(body))
+  })
+
+  t.teardown(server.close.bind(server))
+
+  server.listen(0)
+  await once(server, 'listening')
+
+  const controller = new NPMAbortController()
+  const signal = controller.signal
+  controller.abort()
+
+  try {
+    await fetch(`http://localhost:${server.address().port}`, {
+      signal
+    })
+  } catch (e) {
+    t.equal(e.code, DOMException.ABORT_ERR)
+  }
+})