tts-workshop/packages/extract/src/download.test.ts

import { afterEach, describe, expect, it, vi } from 'vitest';
import type { AssetRef } from '@tts/shared';
import { downloadAll, downloadAsset, guessMimeType } from './download.js';

const ref = (url: string): AssetRef => ({
  kind: 'image',
  url,
  ownerGuid: 'g1',
});

function blobResponse(): Response {
  return new Response(new Blob(['data']), { status: 200 });
}

afterEach(() => {
  vi.unstubAllGlobals();
});

describe('guessMimeType', () => {
  it('maps common image extensions', () => {
    expect(guessMimeType('https://example.com/a.png')).toBe('image/png');
    expect(guessMimeType('https://example.com/a.jpg')).toBe('image/jpeg');
    expect(guessMimeType('https://example.com/a.jpeg')).toBe('image/jpeg');
    expect(guessMimeType('https://example.com/a.gif')).toBe('image/gif');
    expect(guessMimeType('https://example.com/a.webp')).toBe('image/webp');
    expect(guessMimeType('https://example.com/a.pdf')).toBe('application/pdf');
  });

  it('ignores query strings when reading the extension', () => {
    expect(guessMimeType('https://example.com/a.png?v=2')).toBe('image/png');
  });

  it('falls back to octet-stream for unknown extensions', () => {
    expect(guessMimeType('https://example.com/a.xyz')).toBe(
      'application/octet-stream',
    );
    expect(guessMimeType('https://example.com/noext')).toBe(
      'application/octet-stream',
    );
  });
});

describe('downloadAsset', () => {
  it('returns a blob on success', async () => {
    vi.stubGlobal('fetch', vi.fn().mockResolvedValue(blobResponse()));
    const blob = await downloadAsset('https://example.com/a.png');
    expect(blob).toBeInstanceOf(Blob);
  });

  it('throws on a non-OK response', async () => {
    vi.stubGlobal(
      'fetch',
      vi.fn().mockResolvedValue(new Response(null, { status: 404 })),
    );
    await expect(downloadAsset('https://example.com/a.png')).rejects.toThrow(
      'Failed to download asset (404)',
    );
  });
});

describe('downloadAll', () => {
  it('downloads every ref and reports progress', async () => {
    vi.stubGlobal('fetch', vi.fn().mockImplementation(() => blobResponse()));
    const refs = [ref('https://example.com/1.png'), ref('https://example.com/2.png')];
    const progress: number[] = [];
    const results = await downloadAll(refs, {
      concurrency: 2,
      onProgress: (p) => progress.push(p.done),
    });
    expect(results).toHaveLength(2);
    expect(progress).toEqual([1, 2]);
  });

  it('respects the concurrency limit', async () => {
    let inFlight = 0;
    let maxInFlight = 0;
    const fetchMock = vi.fn().mockImplementation(async () => {
      inFlight += 1;
      maxInFlight = Math.max(maxInFlight, inFlight);
      await new Promise((r) => setTimeout(r, 5));
      inFlight -= 1;
      return blobResponse();
    });
    vi.stubGlobal('fetch', fetchMock);

    const refs = Array.from({ length: 6 }, (_, i) =>
      ref(`https://example.com/${i}.png`),
    );
    await downloadAll(refs, { concurrency: 2 });
    expect(maxInFlight).toBeLessThanOrEqual(2);
  });
});