singulure/test.js

A tiny JavaScript utility to ensure a function can only be called a single time — forever.

import { singulure } from './index.js';

let count = 0;
const increment = singulure(() => {
  count++;
  return count;
});

function assert(condition, message) {
  if (!condition) throw new Error(message);
}

assert(increment() === 1, 'First call should return 1');
assert(increment() === 1, 'Second call should still return 1');
assert(increment() === 1, 'Third call should still return 1');

console.log('All tests passed!');