export default function createCounter(n) {
  throw new Error('Not implemented');
}

import createCounter from './file';

describe('createCounter', () => {
  test('increments sequentially', () => {
    const counter = createCounter(10);
    expect(counter()).toBe(10);
    expect(counter()).toBe(11);
    expect(counter()).toBe(12);
  });

  test('works with negative numbers', () => {
    const counter = createCounter(-2);
    expect(counter()).toBe(-2);
    expect(counter()).toBe(-1);
    expect(counter()).toBe(0);
  });

  test('separate counters maintain independent state', () => {
    const c1 = createCounter(0);
    const c2 = createCounter(100);
    expect(c1()).toBe(0);
    expect(c2()).toBe(100);
    expect(c1()).toBe(1);
    expect(c2()).toBe(101);
  });
});