asyncio, Tulip issue 131: as_completed() and wait() now raises a TypeError if

the list of futures is not a list but a Future, Task or coroutine object

Lib/asyncio/tasks.py

@@ -358,6 +358,8 @@ def wait(fs, *, loop=None, timeout=None, return_when=ALL_COMPLETED):
     Note: This does not raise TimeoutError! Futures that aren't done
     when the timeout occurs are returned in the second set.
     """
+    if isinstance(fs, futures.Future) or iscoroutine(fs):
+        raise TypeError("expect a list of futures, not %s" % type(fs).__name__)
     if not fs:
         raise ValueError('Set of coroutines/Futures is empty.')
 
@@ -474,6 +476,8 @@ def as_completed(fs, *, loop=None, timeout=None):
 
     Note: The futures 'f' are not necessarily members of fs.
     """
+    if isinstance(fs, futures.Future) or iscoroutine(fs):
+        raise TypeError("expect a list of futures, not %s" % type(fs).__name__)
     loop = loop if loop is not None else events.get_event_loop()
     deadline = None if timeout is None else loop.time() + timeout
     todo = {async(f, loop=loop) for f in set(fs)}