Creating an encrypted secret with libsodium in a Jest unit test fails: TypeError: unexpected type, use Uint8Array

Question

I want to encode a secret for the GitHub API repository secret endpoint. The code is straight from the docs:

const sodium = require('tweetsodium');

const key = "base64-encoded-public-key";
const value = "plain-text-secret";

// Convert the message and key to Uint8Array's (Buffer implements that interface)
const messageBytes = Buffer.from(value);
const keyBytes = Buffer.from(key, 'base64');

// Encrypt using LibSodium.
const encryptedBytes = sodium.seal(messageBytes, keyBytes);

// Base64 the encrypted secret
const encrypted = Buffer.from(encryptedBytes).toString('base64');

console.log(encrypted);

I use Jest for running a unit test for this code. With Jest I get a TypeError: unexpected type, use Uint8Array error. Without jest the code runs fine.

I would like to unit test my code. How can I make it runnable in Jest?

Answer 1

This GitHub issue explains the error:

As mentioned here, this looks like the testing framework has its own Buffer implementation that is not based on Uint8Array. All functions in TweetNaCl-js expect arguments to be Uint8Arrays and it checks for it here: https://github.com/dchest/tweetnacl-js/blob/master/nacl-fast.js#L2150

This is apparently a known bug in the jest framework. You can solve it with the jest-environment-uint8array dependency and adding a test environment to package.json:

  "jest": {
    "testEnvironment": "jest-environment-uint8array",
    "testTimeout": 10000
  },