fetch: wpt tests that are failing

Description

import { fetch, setGlobalOrigin } from 'undici'
import assert from 'assert'

setGlobalOrigin('http://localhost:3000')

const controller = new AbortController();
const signal = controller.signal;
controller.abort();

const log = [];

await Promise.all([
	fetch('../resources/data.json', { signal }).then(
		() => assert_unreached("Fetch must not resolve"),
		() => log.push('fetch-reject')
	),
	Promise.resolve().then(() => log.push('next-microtask'))
]);

assert.deepStrictEqual(log, ['fetch-reject', 'next-microtask']);

Contributor guide

Tech stack

javascript

Domain

backend

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-2 days

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

JavaScriptNode.jsfetch APIAbortController

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

45

Research direction

Examine the fetch implementation in lib/fetch/index.js, specifically the abort handling at lines 126 and 304. Understand the flow of signal.aborted checks and promise rejection timing. Consider the microtask queue order and whether the fetch function resolves before the next microtask. Look at the original issue #1664 (comment) for context. Write a fix that ensures fetch rejects synchronously (or in the current microtask) when signal is already aborted.