new_contents: import unittest
  from pyramid import testing
  
  class Test_airbrake_tween_factory(unittest.TestCase):
      def setUp(self):
          self.config = testing.setUp(settings={'airbrake.api_key': '01234'})
          self.registry = self.config.registry
  
      def _callFUT(self):
          from pyramid_airbrake import airbrake_tween_factory
          return airbrake_tween_factory(None, self.registry)
  
      def test_no_recipients(self):
          handler = self._callFUT()
          assert handler.__name__ == 'airbrake_tween'
  
  
  class DummyConfig(object):
      def __init__(self):
          self.tweens = []
          self.registry = self
          self.settings = {}
  
      def add_tween(self, factory, under=None, over=None):
          self.tweens.append((factory, under, over))
  
subject: Add first rudimentary test