test: fix beforeEachTemplate's fetch implementation

Signed-off-by: Tierney Cyren <hello@bnb.im>

Author: bnb

core/util/dev/beforeEachTemplate.js

@@ -1,5 +1,5 @@
 const dns = require('node:dns');
-const { MockAgent, setGlobalDispatcher } = require('undici');
+const { fetch: undiciFetch, MockAgent, setGlobalDispatcher } = require('undici');
 
 const staticIndex = require('../../test/data/static/index.json');
 const staticSchedule = require('../../test/data/static/schedule.json');
@@ -8,11 +8,16 @@ function beforeEachTemplate() {
 	// this fixes a bug in Node.js - it should be fixed _eventually_ and can be removed: https://github.com/nodejs/undici/issues/1248
 	dns.setDefaultResultOrder('ipv4first');
 
-	// this mock agent stuff isn't actually working for... some unkown reason
 	const mockAgent = new MockAgent();
 	mockAgent.disableNetConnect();
 	setGlobalDispatcher(mockAgent);
 
+	// Node.js's built-in globalThis.fetch uses a bundled copy of undici separate from
+	// the npm package, so setGlobalDispatcher above doesn't affect it. Replacing it here
+	// ensures all fetch calls (including those that fall through to globalThis.fetch in
+	// optionsParser) go through the mock dispatcher.
+	globalThis.fetch = undiciFetch;
+
 	const defaultIndexMock = mockAgent.get('https://nodejs.org');
 	defaultIndexMock
 		.intercept({ path: '/dist/index.json' })
@@ -25,13 +30,11 @@ function beforeEachTemplate() {
 		.intercept({ path: '/nodejs/Release/master/schedule.json' })
 		.reply(200, staticSchedule);
 
-	const customIndexMock = mockAgent.get('https://bnb.im');
-	customIndexMock
+	const customMock = mockAgent.get('https://bnb.im');
+	customMock
 		.intercept({ path: '/dist/index.json' })
 		.reply(200, staticIndex);
-
-	const customScheduleMock = mockAgent.get('https://bnb.im');
-	customScheduleMock
+	customMock
 		.intercept({ path: '/dist/schedule.json' })
 		.reply(200, staticSchedule);
 }