feat: add bidirectional ICO image converter

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

test/converters/ico.test.js

@@ -0,0 +1,99 @@
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import os from 'node:os';
+import sharp from 'sharp';
+import { registerIcoConverter, encodeIcoFromInput, DEFAULT_ICON_SIZE } from '../../src/converters/ico.js';
+import { resolve, listTargetFormats } from '../../src/converters/registry.js';
+import { detectInputMime } from '../../src/mime.js';
+
+let tmpDir;
+
+beforeAll(async () => {
+  registerIcoConverter();
+  tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'converter-ico-'));
+});
+
+afterAll(async () => {
+  await fs.rm(tmpDir, { recursive: true, force: true });
+});
+
+describe('ICO converter registration', () => {
+  it('registers ico as both a source and a target for every image format', () => {
+    expect(listTargetFormats('ico')).toContain('png');
+    expect(listTargetFormats('ico')).toContain('jpg');
+    expect(listTargetFormats('png')).toContain('ico');
+    expect(listTargetFormats('jpg')).toContain('ico');
+  });
+});
+
+describe('encodeIcoFromInput', () => {
+  it('defaults to a 256x256 icon when no size is given', async () => {
+    const inputPath = path.join(import.meta.dirname, '..', 'fixtures', 'sample.png');
+    const icoBuffer = await encodeIcoFromInput(inputPath);
+
+    const outputPath = path.join(tmpDir, 'default-size.ico');
+    await fs.writeFile(outputPath, icoBuffer);
+    const detected = await detectInputMime(outputPath);
+    expect(detected.mime).toBe('image/x-icon');
+  });
+
+  it('produces an icon at the requested size', async () => {
+    const inputPath = path.join(import.meta.dirname, '..', 'fixtures', 'sample.png');
+    const icoBuffer = await encodeIcoFromInput(inputPath, 32);
+
+    const { decodeIco } = await import('icojs');
+    const [image] = await decodeIco(icoBuffer, 'image/png');
+    expect(image.width).toBe(32);
+    expect(image.height).toBe(32);
+  });
+});
+
+describe('ico -> image conversion', () => {
+  it('converts an ICO fixture to PNG, picking the largest embedded image', async () => {
+    const source = path.join(import.meta.dirname, '..', 'fixtures', 'sample.png');
+    const icoPath = path.join(tmpDir, 'multi.ico');
+
+    const small = await sharp(source).resize(16, 16).png().toBuffer();
+    const large = await sharp(source).resize(48, 48).png().toBuffer();
+    const { encodeIco } = await import('icojs');
+    await fs.writeFile(icoPath, Buffer.from(await encodeIco([{ buffer: small }, { buffer: large }])));
+
+    const outputPath = path.join(tmpDir, 'from-ico.png');
+    const entry = resolve('ico', 'png');
+    await entry.convert(icoPath, outputPath);
+
+    const meta = await sharp(outputPath).metadata();
+    expect(meta.width).toBe(48);
+    expect(meta.height).toBe(48);
+  });
+});
+
+describe('image -> ico conversion', () => {
+  it('converts a PNG fixture to a valid ICO at the requested size', async () => {
+    const inputPath = path.join(import.meta.dirname, '..', 'fixtures', 'sample.png');
+    const outputPath = path.join(tmpDir, 'output.ico');
+    const entry = resolve('png', 'ico');
+
+    await entry.convert(inputPath, outputPath, { iconSize: 48 });
+
+    const detected = await detectInputMime(outputPath);
+    expect(detected.mime).toBe('image/x-icon');
+
+    const { decodeIco } = await import('icojs');
+    const [image] = await decodeIco(await fs.readFile(outputPath), 'image/png');
+    expect(image.width).toBe(48);
+  });
+
+  it('defaults to 256px when no iconSize is given', async () => {
+    const inputPath = path.join(import.meta.dirname, '..', 'fixtures', 'sample.png');
+    const outputPath = path.join(tmpDir, 'output-default.ico');
+    const entry = resolve('png', 'ico');
+
+    await entry.convert(inputPath, outputPath);
+
+    const { decodeIco } = await import('icojs');
+    const [image] = await decodeIco(await fs.readFile(outputPath), 'image/png');
+    expect(image.width).toBe(DEFAULT_ICON_SIZE);
+  });
+});