asyncio/websocket.py not compatible with Python 3.7 syntax changes

This change in Python 3.7:

Backwards incompatible syntax changes:

async and await are now reserved keywords.

Broke this code block in asyncio/websocket.py:

if hasattr(asyncio, 'ensure_future'):
    ensure_future = asyncio.ensure_future
else:  # Deprecated since Python 3.4.4
    ensure_future = asyncio.async

Example failure log:

Traceback (most recent call last):
 File REDACTED, line 18, in <module>
   from autobahn.asyncio.websocket import WebSocketServerFactory, WebSocketServerProtocol
 File “/usr/local/lib/python3.7/site-packages/autobahn/asyncio/__init__.py”, line 36, in <module>
   from autobahn.asyncio.websocket import \
 File “/usr/local/lib/python3.7/site-packages/autobahn/asyncio/websocket.py”, line 52
   ensure_future = asyncio.async
                               ^
SyntaxError: invalid syntax

I fixed the issue locally by just deleting the old import, but I don’t know what preferred fix in autobahn official library is. It would probably work to use getattr(asyncio, “async”) to preserve backwards compatibility while still respecting the new Python 3.7 syntax rules.

[nicolas-leydet]

from @meejah We will want to support Python 3.4 for now

The fix proposed by @Ardonius should do exactly that:

if hasattr(asyncio, 'ensure_future'):
    ensure_future = asyncio.ensure_future
else:  # Deprecated since Python 3.4.4
    ensure_future = getattr(asyncio, "async")

[agronholm]

Even if I use the latest version, the test suite still fails because it tries to import a nonexistent module (asyncio.test_utils).