text: const expect = require('expect');
  const isNil = require('./isNil.js');
  
  test('isNil is a Function', () => {
    expect(isNil).toBeInstanceOf(Function);
  });
  test('Returns true for null', () => {
    expect(isNil(null)).toBeTruthy();
  });
  test('Returns true for undefined', () => {
    expect(isNil(undefined)).toBeTruthy();
  });
  test('Returns false for an empty string', () => {
    expect(isNil('')).toBeFalsy();
  });
  