Update custom_sell to custom_exit

tests/strategy/strats/broken_strats/broken_futures_strategies.py

@@ -1,4 +1,9 @@
-# The strategy which fails to load due to non-existent dependency
+"""
+The strategies here are minimal strategies designed to fail loading in certain conditions.
+They are not operational, and don't aim to be.
+"""
+
+from datetime import datetime
 
 from pandas import DataFrame
 
@@ -14,3 +19,13 @@ class TestStrategyNoImplements(IStrategy):
 class TestStrategyNoImplementSell(TestStrategyNoImplements):
     def populate_entry_trend(self, dataframe: DataFrame, metadata: dict) -> DataFrame:
         return super().populate_entry_trend(dataframe, metadata)
+
+
+class TestStrategyImplementCustomSell(TestStrategyNoImplementSell):
+    def populate_exit_trend(self, dataframe: DataFrame, metadata: dict) -> DataFrame:
+        return super().populate_exit_trend(dataframe, metadata)
+
+    def custom_sell(self, pair: str, trade, current_time: datetime,
+                    current_rate: float, current_profit: float,
+                    **kwargs):
+        return False