Perf: cache Telegram MTProto Key across build

Build/lib/mtproto-auth-key-store.test.ts

@@ -0,0 +1,52 @@
+import { describe, it } from 'mocha';
+import { expect } from 'earl';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { randomBytes } from 'node:crypto';
+
+import { createMTProtoAuthKeyStore } from './mtproto-auth-key-store';
+
+function tmpStorePath() {
+  return path.join(fs.mkdtempSync(path.join(os.tmpdir(), 'mtproto-auth-key-')), 'keys');
+}
+
+describe('mtproto auth key store', () => {
+  it('round-trips a key per DC and survives reopening the directory', async () => {
+    const dir = tmpStorePath();
+    const dc1 = randomBytes(256);
+    const dc2 = randomBytes(256);
+
+    const store = createMTProtoAuthKeyStore(dir);
+    expect(await store.load(1)).toEqual(null);
+    await store.save(1, dc1);
+    await store.save(2, dc2);
+    expect((await store.load(1))?.equals(dc1)).toEqual(true);
+    expect((await store.load(2))?.equals(dc2)).toEqual(true);
+
+    // a fresh handle on the same directory is what the next build sees
+    const reopened = createMTProtoAuthKeyStore(dir);
+    expect((await reopened.load(1))?.equals(dc1)).toEqual(true);
+  });
+
+  it('replaces on save and forgets on drop', async () => {
+    const store = createMTProtoAuthKeyStore(tmpStorePath());
+    const first = randomBytes(256);
+    const second = randomBytes(256);
+
+    await store.save(4, first);
+    await store.save(4, second);
+    expect((await store.load(4))?.equals(second)).toEqual(true);
+
+    await store.drop(4);
+    expect(await store.load(4)).toEqual(null);
+    // dropping an absent key is a no-op
+    await store.drop(4);
+  });
+
+  it('treats a key of the wrong size as absent', async () => {
+    const store = createMTProtoAuthKeyStore(tmpStorePath());
+    await store.save(5, randomBytes(16));
+    expect(await store.load(5)).toEqual(null);
+  });
+});