const mock = () => {
    let storage = {};
    return {
  getItem: key => (key in storage ? storage[key] : null),
             setItem: (key, value) => (storage[key] = value || ''),
             removeItem: key => delete storage[key],
             clear: () => (storage = {})
    };
  };

  Object.defineProperty(window, 'localStorage', { value: mock() });
  Object.defineProperty(window, 'sessionStorage', { value: mock() });
  Object.defineProperty(window, 'getComputedStyle', {
        value: () => ['-webkit-appearance'],

  });