fix: ensure BytesFactory does not produce padded array (#397)

* ensure BytesFactory does not produce padded array

* add newline

.gitignore

@@ -31,3 +31,4 @@ coverage/
 
 # Turborepo
 .turbo
+dist

packages/utils/src/factories.test.ts

@@ -99,3 +99,12 @@ describe('VerificationAddEthAddressBodyFactory', () => {
     expect(verifiedAddress._unsafeUnwrap()).toEqual(body.addressArray());
   });
 });
+
+describe('BytesFactory', () => {
+  describe('with length', () => {
+    test('succeeds with unpadded little endian', () => {
+      const bytes = Factories.Bytes.build({}, { transient: { length: 32 } });
+      expect(bytes[bytes.length - 1]).not.toEqual(0);
+    });
+  });
+});

packages/utils/src/factories.ts

@@ -10,13 +10,14 @@ import { toFarcasterTime } from './time';
 import { toTsHash } from './tsHash';
 import { makeVerificationEthAddressClaim, VerificationEthAddressClaim } from './verifications';
 
-/* eslint-disable security/detect-object-injection */
 const BytesFactory = Factory.define<Uint8Array, { length?: number }>(({ transientParams }) => {
-  const length = transientParams.length ?? 8;
+  const length = transientParams.length ?? faker.datatype.number({ max: 64, min: 1 });
   const bytes = new Uint8Array(length);
-  for (let i = 0; i < bytes.byteLength; i++) {
-    bytes[i] = faker.datatype.number({ max: 255, min: 0 });
+  for (let i = 0; i < bytes.length - 1; i++) {
+    bytes.set([faker.datatype.number({ max: 255, min: 0 })], i);
   }
+  // Ensure that the most significant byte is not 0 (i.e. is not padding)
+  bytes.set([faker.datatype.number({ max: 255, min: 1 })], bytes.length - 1);
   return bytes;
 });