fakesync

fakesync wraps synchronous or async functions so they behave like async calls with configurable delay and simulated failures. It's intentionally small and dependency-free — useful for frontend development and tests.

Quick summary

• registerDefaults(options) — set global minDelay, maxDelay, failRate.
• register(funcs, options) — returns a new object mapping each function to a Promise-returning wrapper which applies the delay and failure rules.

Installation

npm install fakesync

Basic usage

const fakesync = require('fakesync'); // or require('./index') if installed locally

fakesync.registerDefaults({ minDelay: 100, maxDelay: 1000, failRate: 0.1 });

// your function
function getUser(id) {
  return { id, name: 'Alice' };
}

// `api` contains the wrapped, Promise-returning functions
const api = fakesync.register({ getUser });

// call the wrapped function
(async () => {
  try {
    const user = await api.getUser(1);
    console.log(user);
  } catch (err) {
    console.error('Request failed:', err.message);
  }
})();

TypeScript

This package ships index.d.ts so TypeScript can infer the names and signatures of registered functions. register returns a strongly-typed object mapping your original functions to Promise-returning versions.

Notes

• register no longer mutates the exported fakesync object; it returns a new API object. This keeps the exported module stable and improves type safety.
• Behavior: each wrapped function waits a random delay between minDelay and maxDelay and rejects with Error('Simulated failure') with probability failRate.

Contributions

Contributions and issues welcome. Create a PR or open an issue on GitHub.