'L{client.ContentDecoderAgent} sets the I{Accept-Encoding} header to the
names of the available decoder objects.'

def test_acceptHeaders(self):

    agent = client.ContentDecoderAgent(self.agent, [('decoder1', Decoder1), ('decoder2', Decoder2)])
    agent.request('GET', 'http://example.com/foo')
    protocol = self.protocol
    self.assertEqual(len(protocol.requests), 1)
    (req, res) = protocol.requests.pop()
    self.assertEqual(req.headers.getRawHeaders('accept-encoding'), ['decoder1,decoder2'])
