feat: best-effort artwork disk cache

server/test/artwork.test.ts

@@ -0,0 +1,78 @@
+import { describe, it, expect } from 'vitest'
+import { mkdtempSync, rmSync, existsSync, readFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import path from 'node:path'
+import { cacheArtwork } from '../src/artwork.js'
+
+function tempDir(): string {
+  return mkdtempSync(path.join(tmpdir(), 'rs-artwork-'))
+}
+
+function imageFetch(calls: { count: number }): typeof fetch {
+  return (async () => {
+    calls.count++
+    return new Response(new Uint8Array([0xff, 0xd8, 0xff, 0xe0]), {
+      status: 200,
+      headers: { 'content-type': 'image/jpeg' },
+    })
+  }) as typeof fetch
+}
+
+describe('cacheArtwork', () => {
+  it('downloads and stores by url hash with content-type extension', async () => {
+    const dir = tempDir()
+    try {
+      const calls = { count: 0 }
+      const file = await cacheArtwork(dir, 'https://img.discogs.com/a.jpg', imageFetch(calls))
+      expect(file).toMatch(/^[0-9a-f]{64}\.jpg$/)
+      expect(existsSync(path.join(dir, file as string))).toBe(true)
+    } finally {
+      rmSync(dir, { recursive: true, force: true })
+    }
+  })
+
+  it('second call for same url does not refetch', async () => {
+    const dir = tempDir()
+    try {
+      const calls = { count: 0 }
+      const fetcher = imageFetch(calls)
+      await cacheArtwork(dir, 'https://img.discogs.com/a.jpg', fetcher)
+      const again = await cacheArtwork(dir, 'https://img.discogs.com/a.jpg', fetcher)
+      expect(calls.count).toBe(1)
+      expect(again).not.toBeNull()
+    } finally {
+      rmSync(dir, { recursive: true, force: true })
+    }
+  })
+
+  it('returns null for empty url and fetch failures without throwing', async () => {
+    const dir = tempDir()
+    try {
+      expect(await cacheArtwork(dir, '', imageFetch({ count: 0 }))).toBeNull()
+      const failing = (async () => {
+        throw new TypeError('fetch failed')
+      }) as unknown as typeof fetch
+      expect(await cacheArtwork(dir, 'https://x/y.jpg', failing)).toBeNull()
+      const notFound = (async () => new Response('nope', { status: 404 })) as unknown as typeof fetch
+      expect(await cacheArtwork(dir, 'https://x/y.jpg', notFound)).toBeNull()
+    } finally {
+      rmSync(dir, { recursive: true, force: true })
+    }
+  })
+
+  it('stores non-jpeg types with correct extension', async () => {
+    const dir = tempDir()
+    try {
+      const fetcher = (async () =>
+        new Response(new Uint8Array([0x89, 0x50]), {
+          status: 200,
+          headers: { 'content-type': 'image/png' },
+        })) as typeof fetch
+      const file = await cacheArtwork(dir, 'https://img.discogs.com/a.png', fetcher)
+      expect(file).toMatch(/\.png$/)
+      expect(readFileSync(path.join(dir, file as string)).length).toBeGreaterThan(0)
+    } finally {
+      rmSync(dir, { recursive: true, force: true })
+    }
+  })
+})