text: const responseHeaders = require('./response-headers');
  
  const next = jest.fn();
  const res = {
    setHeader: jest.fn(),
  };
  
  describe('Resonse headers', () => {
    beforeAll(() => {
      res.setHeader.mockClear();
      responseHeaders(jest.fn(), res, next);
    });
  
    it('should set three headers', () => {
      expect(res.setHeader).toHaveBeenCalledTimes(3);
    });
  
    it('should set XSS header', () => {
      expect(res.setHeader).toHaveBeenCalledWith('X-XSS-Protection', '1;mode=block');
    });
  
    it('should set X-frame header', () => {
      expect(res.setHeader).toHaveBeenCalledWith('X-Frame-Options', 'SAMEORIGIN');
    });
  
    it('should set nosniff header', () => {
      expect(res.setHeader).toHaveBeenCalledWith('X-Content-Type-Options', 'nosniff');
    });
  });
  