const {counter} = require('./_30s.js'); test('counter is a Function', () => { expect(counter).toBeInstanceOf(Function); }); test('counter does not throw errors', () => { expect(() => { document.body.appendChild(document.createElement('div')); counter('div', 1, 1000, 5, 2000); counter('div', 1000, 1, 5, 2000); counter('div', 1, 1000); }).not.toThrow(TypeError); });