Merge pull request #3649 from minrk/get_dict_single

fix AsyncResult.get_dict for single result

and add tests for single-result and invalid input (multiple results on one engine).

closes  #3646

IPython/parallel/client/asyncresult.py

@@ -191,14 +191,21 b' class AsyncResult(object):'
         """
 
         results = self.get(timeout)
+        if self._single_result:
+            results = [results]
         engine_ids = [ md['engine_id'] for md in self._metadata ]
-        bycount = sorted(engine_ids, key=lambda k: engine_ids.count(k))
-        maxcount = bycount.count(bycount[-1])
-        if maxcount > 1:
-            raise ValueError("Cannot build dict, %i jobs ran on engine #%i"%(
-                    maxcount, bycount[-1]))
+        
+        
+        rdict = {}
+        for engine_id, result in zip(engine_ids, results):
+            if engine_id in rdict:
+                raise ValueError("Cannot build dict, %i jobs ran on engine #%i" % (
+                    engine_ids.count(engine_id), engine_id)
+                )
+            else:
+                rdict[engine_id] = result
 
-        return dict(zip(engine_ids,results))
+        return rdict
 
     @property
     def result(self):

IPython/parallel/tests/test_asyncresult.py

@@ -35,6 +35,9 b' def wait(n):'
     time.sleep(n)
     return n
 
+def echo(x):
+    return x
+
 class AsyncResultTest(ClusterTestCase):
 
     def test_single_result_view(self):
@@ -77,6 +80,20 b' class AsyncResultTest(ClusterTestCase):'
         for eid,r in d.iteritems():
             self.assertEqual(r, 5)
     
+    def test_get_dict_single(self):
+        view = self.client[-1]
+        for v in (range(5), 5, ('abc', 'def'), 'string'):
+            ar = view.apply_async(echo, v)
+            self.assertEqual(ar.get(), v)
+            d = ar.get_dict()
+            self.assertEqual(d, {view.targets : v})
+    
+    def test_get_dict_bad(self):
+        ar = self.client[:].apply_async(lambda : 5)
+        ar2 = self.client[:].apply_async(lambda : 5)
+        ar = self.client.get_result(ar.msg_ids + ar2.msg_ids)
+        self.assertRaises(ValueError, ar.get_dict)
+    
     def test_list_amr(self):
         ar = self.client.load_balanced_view().map_async(wait, [0.1]*5)
         rlist = list(ar)