Add method "to_datetime" to TimeRange.

freqtrade/configuration/timerange.py

@@ -4,6 +4,7 @@ This module contains the argument manager class
 import logging
 import re
 from typing import Optional
+from datetime import datetime, timezone
 
 import arrow
 
@@ -33,6 +34,10 @@ class TimeRange:
         return (self.starttype == other.starttype and self.stoptype == other.stoptype
                 and self.startts == other.startts and self.stopts == other.stopts)
 
+    def to_datetime(self) -> (datetime, datetime):
+        return datetime.fromtimestamp(self.startts, timezone.utc), \
+               datetime.fromtimestamp(self.stopts, timezone.utc)
+
     def subtract_start(self, seconds: int) -> None:
         """
         Subtracts <seconds> from startts if startts is set.

freqtrade/data/history/history_utils.py

@@ -287,9 +287,12 @@ def refresh_backtest_ohlcv_data(exchange: Exchange, pairs: List[str], timeframes
                         f'Deleting existing data for pair {pair}, interval {timeframe}.')
 
             logger.info(f'Downloading pair {pair}, interval {timeframe}.')
+            # What happens when until should be None?
+            since, until = timerange.to_datetime()
             _download_pair_history(datadir=datadir, exchange=exchange,
                                    pair=pair, timeframe=str(timeframe),
-                                   timerange=timerange, data_handler=data_handler)
+                                   since=since, until=until,
+                                   data_handler=data_handler)
     return pairs_not_available