ENH: Provides a more descriptive error if market_open or market_close are provided a non-keyword argument that is not a datetime.timedelta

tests/utils/test_events.py

@@ -74,6 +74,11 @@ class TestUtils(TestCase):
         with self.assertRaises(ValueError):
             _build_offset(datetime.timedelta(minutes=1), {'minutes': 1}, None)
 
+    def test_build_offset_exc(self):
+        with self.assertRaises(TypeError):
+            # object() is not an instance of a timedelta.
+            _build_offset(object(), {}, None)
+
     def test_build_offset_kwargs(self):
         kwargs = {'minutes': 1}
         self.assertEqual(

zipline/utils/events.py

@@ -77,8 +77,10 @@ def _build_offset(offset, kwargs, default):
             return datetime.timedelta(**kwargs)
     elif kwargs:
         raise ValueError('Cannot pass kwargs and an offset')
-    else:
+    elif isinstance(offset, datetime.timedelta):
         return offset
+    else:
+        raise TypeError("Must pass 'hours' and/or 'minutes' as keywords")
 
 
 def _build_date(date, kwargs):