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</> Code
Test cases
Language
JavaScript
TypeScript
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); }); });
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