Currently, the documentation for

class aiohttp.web.Response(*, status=200, headers=None, content_type=None, charset=None, body=None, text=None)

states that

content_type (str) – response’s content type. 'text/plain' if text is passed also, 'application/octet-stream' otherwise.

However, if I do not set the text argument (but set the body argument instead) the content_type is not set at all (whereas the documentation says it should be automatically set to application/octet-stream).

Python 3.5.1 and aiohttp 0.21.0