const {isPromiseLike} = require('./_30s.js'); test('isPromiseLike is a Function', () => { expect(isPromiseLike).toBeInstanceOf(Function); }); test('Returns true for a promise-like object', () => { expect( isPromiseLike({ then() { return ''; } }) ).toBeTruthy(); }); test('Returns false for an empty object', () => { expect(isPromiseLike({})).toBeFalsy(); }); test('Returns false for a normal function', () => { expect(isPromiseLike(Math.max)).toBeFalsy(); });