'Responses with no length do not have a default content-type applied.'

def test_noDefaultContentTypeOnZeroLengthResponse(self):

    resrc = ZeroLengthResource()
    resrc.putChild('', resrc)
    site = server.Site(resrc)
    d = DummyChannel()
    d.site = site
    request = server.Request(d, 1)
    request.site = site
    request.setHost('example.com', 80)
    request.gotLength(0)
    request.requestReceived('GET', '/', 'HTTP/1.1')
    self.assertNotIn('content-type', request.transport.written.getvalue().lower())
