old_contents: /*global describe, it, before, beforeEach, after, afterEach */
  import React from 'react';
  import { configure, shallow } from 'enzyme';
  import Adapter from 'enzyme-adapter-react-15';
  
  import { _Header_ } from './index';
  
  configure({ adapter: new Adapter() });
  
  beforeEach(() => {
      global.$STM_Config = {};
  });
  
  describe('Header', () => {
      it('contains class .header', () => {
          global.$STM_Config = { read_only_mode: false };
          expect(shallow(<_Header_ pathname={'whatever'} />).is('.Header')).toBe(
              true
          );
      });
  });
  
new_contents: /*global describe, it, before, beforeEach, after, afterEach */
  import React from 'react';
  import { configure, shallow } from 'enzyme';
  import Adapter from 'enzyme-adapter-react-15';
  
  import { _Header_ } from './index';
  
  configure({ adapter: new Adapter() });
  
  beforeEach(() => {
      global.$STM_Config = {};
  });
  
  describe('Header', () => {
      it('contains class .header', () => {
          global.$STM_Config = { read_only_mode: false };
          const header = shallow(<_Header_ pathname={'whatever'} />);
          console.log(header.closest('header.header'));
          expect(header.closest('header.header').length).toBe(1);
      });
  });
  
subject: Fix failing test