const expect = require('expect'); const isStream = require('./isStream.js'); const fs = require('fs'); test('isStream is a Function', () => { expect(isStream).toBeInstanceOf(Function); }); test('isStream returns true for streams', () => { expect(isStream(fs.createReadStream('isStream.js'))).toBeTruthy(); }); test('isStream returns false for non-streams', () => { expect(isStream({})).toBeFalsy(); });