text: import React from 'react';
  import renderer from 'react-test-renderer';
  import Navbar from './navbar';
  
  describe('Navbar', () => {
    test('No props', () => {
      const component = renderer.create(<Navbar />);
      const tree = component.toJSON();
      expect(tree).toMatchSnapshot();
    });
  
    test('Make "About" item active', () => {
      const component = renderer.create(<Navbar active='About' />);
      const tree = component.toJSON();
      expect(tree).toMatchSnapshot();
    });
  
    test('Make "Introduction" item active', () => {
      const component = renderer.create(<Navbar active='Introduction' />);
      const tree = component.toJSON();
      expect(tree).toMatchSnapshot();
    });
  });
  