How to mock @serverless-stack/node/config specifically Config.Secret?

Question

I am trying to use mongodb-memory-server but using secret as below,

import { Config, StackContext } from "@serverless-stack/resources";

export default function SecretsStack({ stack }: StackContext) {
  const MONGO_URI = new Config.Secret(stack, "MONGO_URI");

  return { MONGO_URI };
}

How do I mock it up via mongodb-memory-server URI while running it via npm test.

How to mock stuff in sst framework specifically tied to it's components.