fix: mock node fetch with options.body fn

Author: KhafraDev

lib/fetch/index.js

@@ -51,7 +51,6 @@ const EE = require('events')
 const { Readable, pipeline } = require('stream')
 const { isErrored, isReadable } = require('../core/util')
 const { dataURLProcessor } = require('./dataURL')
-const { kIsMockActive } = require('../mock/mock-symbols')
 const { TransformStream } = require('stream/web')
 
 /** @type {import('buffer').resolveObjectURL} */
@@ -1912,7 +1911,7 @@ async function httpNetworkFetch (
         path: url.pathname + url.search,
         origin: url.origin,
         method: request.method,
-        body: fetchParams.controller.dispatcher[kIsMockActive] ? request.body && request.body.source : body,
+        body: fetchParams.controller.dispatcher.isActive ? request.body && request.body.source : body,
         headers: [...request.headersList].flat(),
         maxRedirections: 0,
         bodyTimeout: 300_000,

lib/mock/mock-agent.js

@@ -96,6 +96,12 @@ class MockAgent extends Dispatcher {
     this[kNetConnect] = false
   }
 
+  // This is required to bypass issues caused by using global symbols - see:
+  // https://github.com/nodejs/undici/issues/1447
+  get isActive () {
+    return this[kIsMockActive]
+  }
+
   [kMockAgentSet] (origin, dispatcher) {
     this[kClients].set(origin, new FakeWeakRef(dispatcher))
   }

lib/mock/mock-utils.js

@@ -6,7 +6,6 @@ const {
   kMockAgent,
   kOriginalDispatch,
   kOrigin,
-  kIsMockActive,
   kGetNetConnect
 } = require('./mock-symbols')
 
@@ -302,7 +301,7 @@ function buildMockDispatch () {
   const originalDispatch = this[kOriginalDispatch]
 
   return function dispatch (opts, handler) {
-    if (agent[kIsMockActive]) {
+    if (agent.isActive) {
       try {
         mockDispatch.call(this, opts, handler)
       } catch (error) {