new_contents: import httpretty
  
  from zipa import test_com as t
  
  
  def test_config_zipa():
      t.config.host = 'random'
      t.config.prefix = 'prefix'
      t.config.append_slash = True
      t.config.secure = False
      t.config.headers = {
          'x-custom-header': 'custom-value'
      }
  
      assert t.config['host'] == 'random'
      assert t.config['prefix'] == 'prefix'
      assert t.config['append_slash']
      assert t.config['headers']['x-custom-header'] == 'custom-value'
  
      httpretty.enable()
      httpretty.register_uri(httpretty.GET, 'http://randomprefix/a/', status=200,
                             content_type='application/json', body=u'{"name": "a"}')
  
      assert t.a().name == 'a'
      assert httpretty.last_request().headers['x-custom-header'] == 'custom-value'
  
subject: Add tests for custom headers