MAINT/TEST: Move to_utc from history_cases.py to test_utils.py.

tests/history_cases.py

@@ -8,10 +8,7 @@ import numpy as np
 from zipline.finance.trading import TradingEnvironment
 from zipline.history.history import HistorySpec
 from zipline.protocol import BarData
-
-
-def to_utc(time_str):
-    return pd.Timestamp(time_str, tz='US/Eastern').tz_convert('UTC')
+from zipline.utils.test_utils import to_utc
 
 
 def mixed_frequency_expected_index(count, frequency):

zipline/utils/test_utils.py

@@ -4,6 +4,12 @@ from zipline.finance.blotter import ORDER_STATUS
 
 from six import itervalues
 
+import pandas as pd
+
+
+def to_utc(time_str):
+    return pd.Timestamp(time_str, tz='US/Eastern').tz_convert('UTC')
+
 
 def setup_logger(test, path='test.log'):
     test.log_handler = FileHandler(path)