Refactor start-adjust logic to timerange

freqtrade/configuration/timerange.py

@@ -1,11 +1,14 @@
 """
 This module contains the argument manager class
 """
+import logging
 import re
 from typing import Optional
 
 import arrow
 
+logger = logging.getLogger(__name__)
+
 
 class TimeRange:
     """
@@ -28,9 +31,33 @@ class TimeRange:
                 and self.startts == other.startts and self.stopts == other.stopts)
 
     def subtract_start(self, seconds) -> None:
+        """
+        Subtracts <seconds> from startts if startts is set.
+        :param seconds: Seconds to subtract from starttime
+        :return: None (Modifies the object in place)
+        """
         if self.startts:
             self.startts = self.startts - seconds
 
+    def adjust_start_if_necessary(self, ticker_interval_secs: int, startup_candles: int,
+                                  min_date: arrow.Arrow) -> None:
+        """
+        Adjust startts by <startup_candles> candles.
+        Applies only if no startup-candles have been available.
+        :param ticker_interval_secs: Ticker interval in seconds e.g. `timeframe_to_seconds('5m')`
+        :param startup_candles: Number of candles to move start-date forward
+        :param min_date: Minimum data date loaded. Key kriterium to decide if start-time
+                         has to be moved
+        :return: None (Modifies the object in place)
+        """
+        if (not self.starttype or (startup_candles
+                                   and min_date.timestamp == self.startts)):
+            # If no startts was defined, or test-data starts at the defined test-date
+            logger.warning("Moving start-date by %s candles to account for startup time.",
+                           startup_candles)
+            self.startts = (min_date.timestamp + ticker_interval_secs * startup_candles)
+            self.starttype = 'date'
+
     @staticmethod
     def parse_timerange(text: Optional[str]):
         """

freqtrade/optimize/backtesting.py

@@ -446,15 +446,9 @@ class Backtesting:
             'Loading backtest data from %s up to %s (%s days)..',
             min_date.isoformat(), max_date.isoformat(), (max_date - min_date).days
         )
-        if (not timerange.starttype or (self.required_startup
+        # Adjust startts forward if not enough data is available
-                                        and min_date.timestamp == timerange.startts)):
+        timerange.adjust_start_if_necessary(timeframe_to_seconds(self.ticker_interval),
-            # If no startts was defined, or test-data starts at the defined test-date
+                                            self.required_startup, min_date)
-            logger.warning("Moving start-date by %s candles to account for startup time.",
-                           self.required_startup)
-            timerange.startts = (min_date.timestamp
-                                 + timeframe_to_seconds(self.ticker_interval)
-                                 * self.required_startup)
-            timerange.starttype = 'date'
 
         for strat in self.strategylist:
             logger.info("Running backtesting for Strategy %s", strat.get_strategy_name())