Raise informative error when using as_completed with non-futures (#797)

dask · Jan 9, 2017 · 6cc922f · 6cc922f
1 parent b9c01bb
commit 6cc922f
Show file tree

Hide file tree

Showing 2 changed files with 11 additions and 0 deletions.
diff --git a/distributed/client.py b/distributed/client.py
@@ -2363,6 +2363,10 @@ def as_completed(fs):
     fs = list(fs)
     if not fs:
         return
+    non_futures = [f for f in fs if not isinstance(f, Future)]
+    if non_futures:
+        raise TypeError("Using as_completed on non-future objects: %s" %
+                        non_futures)
     if len(set(f.client for f in fs)) == 1:
         loop = first(fs).client.loop
     else:

diff --git a/distributed/tests/test_client.py b/distributed/tests/test_client.py
@@ -403,6 +403,13 @@ def test_as_completed(loop):
             assert list(as_completed([])) == []
 
 
+def test_as_completed_with_non_futures(loop):
+    with cluster() as (s, [a, b]):
+        with Client(('127.0.0.1', s['port']), loop=loop) as c:
+            with pytest.raises(TypeError):
+                list(as_completed([1, 2, 3]))
+
+
 def test_wait_sync(loop):
     with cluster() as (s, [a, b]):
         with Client(('127.0.0.1', s['port']), loop=loop) as c: