const expect = require('expect'); const {countOccurrences} = require('./_30s.js'); test('countOccurrences is a Function', () => { expect(countOccurrences).toBeInstanceOf(Function); }); test('Counts the occurrences of a value in an array', () => { expect(countOccurrences([1, 1, 2, 1, 2, 3], 1)).toEqual(3); }); test('Works with different types in the same array', () => { expect(countOccurrences([1, 1, 2, 1, 2, 3, '1', true], 1)).toEqual(3); });