Cancelling an upload leaves chunks in flight

Problem Description

src/upload.js uploads a file as a sequence of chunks and accepts an AbortSignal so the user can cancel. Support has seen cancelled uploads continue to consume bandwidth, which suggests the signal is not reaching the per-chunk work, or that further chunks start after the cancel.

The existing test aborts before the upload begins. That is the easy case and it tells us nothing about a cancel that arrives while a chunk is in flight.

Output Specification

Add src/upload.test.js covering cancellation that arrives mid-upload: that the in-flight chunk is told to stop, that no further chunk is started, that the caller sees an abort rather than a normal completion, and that cleanup runs.

Run npm test before you finish; it must pass.

Leave src/upload.basic.test.js in place.

Input Files

Extract the following files before beginning.

=============== FILE: package.json =============== { "name": "uploader", "version": "2.0.4", "private": true, "scripts": { "test": "node --test" } }

=============== FILE: src/upload.js =============== 'use strict';

class AbortError extends Error { constructor() { super('The operation was aborted'); this.name = 'AbortError'; } }

async function uploadAll(chunks, { signal, uploadChunk, onCleanup }) { const receipts = []; try { for (const chunk of chunks) { if (signal.aborted) { throw new AbortError(); } const receipt = await uploadChunk(chunk, signal); if (signal.aborted) { throw new AbortError(); } receipts.push(receipt); } return receipts; } finally { if (onCleanup) { onCleanup({ uploaded: receipts.length, aborted: signal.aborted }); } } }

module.exports = { uploadAll, AbortError };

=============== FILE: src/upload.basic.test.js =============== 'use strict';

const test = require('node:test'); const assert = require('node:assert/strict'); const { uploadAll } = require('./upload');

test('uploads every chunk when not cancelled', async () => { const started = []; const receipts = await uploadAll(['a', 'b'], { signal: new AbortController().signal, uploadChunk: async (chunk) => { started.push(chunk); return receipt-${chunk}; }, });

assert.deepEqual(started, ['a', 'b']); assert.deepEqual(receipts, ['receipt-a', 'receipt-b']); });

test('rejects when aborted before it starts', async () => { const controller = new AbortController(); controller.abort();

await assert.rejects( () => uploadAll(['a'], { signal: controller.signal, uploadChunk: async () => 'x' }), { name: 'AbortError' }, ); });