diff --git a/zipline/gens/feed.py b/zipline/gens/feed.py
index cdc2f7b7..0d0b0bec 100644
--- a/zipline/gens/feed.py
+++ b/zipline/gens/feed.py
@@ -25,7 +25,6 @@ def FeedGen(stream_in, source_ids):
     message and yield it.  
     """
     
-    assert isinstance(stream_in, types.GeneratorType)
     assert isinstance(source_ids, list)
 
     # Set up an internal queue for each expected source.
@@ -109,7 +108,7 @@ def pop_oldest(sources):
             oldest_event = older(oldest_event, current_event)
             
     # Pop the oldest event we found from its queue and return it.
-    return sources[oldest_event.source_id].pop()
+    return sources[oldest_event.source_id].popleft()
 
 # Return the event with the older timestamp.  Break ties by source_id.
 def older(oldest, current):
diff --git a/zipline/gens/test_feed.py b/zipline/gens/test_feed.py
index 1605b6aa..8e6a4ff0 100644
--- a/zipline/gens/test_feed.py
+++ b/zipline/gens/test_feed.py
@@ -6,7 +6,7 @@ import pytz
 
 from unittest2 import TestCase
 from pymongo import Connection, ASCENDING
-from itertools import izip, izip_longest, permutations, cycle
+from itertools import izip, izip_longest, permutations, cycle, chain
 from datetime import datetime, timedelta
 from collections import deque
 
@@ -14,7 +14,7 @@ from zipline import ndict
 from zipline.gens.feed import FeedGen, full, done, queue_is_full,queue_is_done,\
     pop_oldest
 from zipline.gens.utils import stringify_args, assert_datasource_protocol,\
-    assert_trade_protocol, date_gen
+    assert_trade_protocol, date_gen, alternate
 
 import zipline.protocol as zp
 
@@ -96,7 +96,8 @@ class FeedGenTestCase(TestCase):
         Assert that FeedGen's output agrees with expected.
         """
         feed_gen = FeedGen(events, source_ids)
-        assert list(feed_gen) == expected
+        l = list(feed_gen)
+        assert l == expected
         
 
     def test_single_source(self):
@@ -119,38 +120,41 @@ class FeedGenTestCase(TestCase):
         
         self.run_FeedGen(event_gen, expected, source_ids)
     
-    def test_multi_source_interleaved(self):
+    def test_multi_source(self):
         source_ids = ['a', 'b']
         type = zp.DATASOURCE_TYPE.TRADE
 
-        # Set up source 'a'. Outputs 3 events with 2 minute deltas.
+        # Set up source 'a'. Outputs 20 events with 2 minute deltas.
         delta_a = timedelta(minutes = 2)
-        dates_a = list(date_gen(delta = delta_a, n = 3))
+        dates_a = list(date_gen(delta = delta_a, n = 20))
         dates_a.append("DONE")
 
         events_a_args = zip(cycle(['a']), iter(dates_a), cycle([type]))
         events_a = [mock_data_unframe(*args) for args in events_a_args]        
-        event_gen_a = (e for e in events_a)
-
-        # Set up source 'b'. Outputs 4 events with 1 minute deltas.
+        
+        # Set up source 'b'. Outputs 10 events with 1 minute deltas.
         delta_b = timedelta(minutes = 1)
-        dates_b = list(date_gen(delta = delta_b, n = 4))
+        dates_b = list(date_gen(delta = delta_b, n = 10))
         dates_b.append("DONE")
 
         events_b_args = zip(cycle(['b']), iter(dates_b), cycle([type]))
         events_b = [mock_data_unframe(*args) for args in events_b_args]
-        event_gen_b = (e for e in events_b)
-
         
         # The expected output is all non-DONE events in both a and b,
         # sorted first by dt and then by source_id.
         non_dones = events_a[:-1] + events_b[:-1]
         expected = sorted(non_dones, compare_by_dt_source_id)
-        
-        import nose.tools; nose.tools.set_trace()
-        self.run_FeedGen(event_gen, expected, source_ids)
-        
 
+        # Alternating between a and b.
+        interleaved = alternate(iter(events_a), iter(events_b))
+        self.run_FeedGen(interleaved, expected, source_ids)
+
+        # All of a, then all of b.
+
+        sequential = chain(iter(events_a), iter(events_b))
+        self.run_FeedGen(sequential, expected, source_ids)
+    
+        
 #     def test_FeedGen_consistency(self):
         
 #         source_ids = ['a', 'b']
diff --git a/zipline/gens/test_mongods.py b/zipline/gens/test_mongods.py
index 7260fd7d..ea19d90e 100644
--- a/zipline/gens/test_mongods.py
+++ b/zipline/gens/test_mongods.py
@@ -15,15 +15,6 @@ from zipline.gens.utils import stringify_args, assert_datasource_protocol,\
 
 import zipline.protocol as zp
 
-def mock_raw_event(sid, dt):
-    event = {
-        'sid'    : sid,
-        'dt'     : dt,
-        'price'  : 1.0,
-        'volume' : 1
-    }
-    return event
-
 mongo_conn_args = {
     'mongodb_host':  'localhost',
     'mongodb_port':  27017,
diff --git a/zipline/gens/utils.py b/zipline/gens/utils.py
index fd1c8464..1d9a6fd9 100644
--- a/zipline/gens/utils.py
+++ b/zipline/gens/utils.py
@@ -3,7 +3,7 @@ import numbers
 
 from hashlib import md5
 from datetime import datetime, timedelta
-
+from itertools import izip_longest
 from zipline import ndict
 from zipline.protocol import DATASOURCE_TYPE
 
@@ -19,6 +19,13 @@ def mock_raw_event(sid, dt):
 def date_gen(start = datetime(2012, 6, 6, 0), delta = timedelta(minutes = 1), n = 100):
     return (start + i * delta for i in xrange(n))
 
+def alternate(g1, g2):
+    for e1, e2 in izip_longest(g1, g2):
+        if e1 != None:
+            yield e1
+        if e2 != None:
+            yield e2
+
 def stringify_args(*args, **kwargs):
     """Define a unique string for any set of representable args."""
     arg_string = '_'.join([str(arg) for arg in args])