Don't return None from unlimited_stake - 0 handles this just as well

freqtrade/freqtradebot.py

@@ -250,12 +250,13 @@ class FreqtradeBot:
 
         return used_rate
 
-    def get_trade_stake_amount(self, pair) -> Optional[float]:
+    def get_trade_stake_amount(self, pair) -> float:
         """
         Calculate stake amount for the trade
         :return: float: Stake amount
+        :raise: DependencyException if the available stake amount is too low
         """
-        stake_amount: Optional[float]
+        stake_amount: float
         if self.edge:
             stake_amount = self.edge.stake_amount(
                 pair,
@@ -286,20 +287,20 @@ class FreqtradeBot:
                             self.config['tradable_balance_ratio']) - val_tied_up
         return available_amount
 
-    def _calculate_unlimited_stake_amount(self) -> Optional[float]:
+    def _calculate_unlimited_stake_amount(self) -> float:
         """
         Calculate stake amount for "unlimited" stake amount
-        :return: None if max number of trades reached
+        :return: 0 if max number of trades reached, else stake_amount to use.
         """
         free_open_trades = self.get_free_open_trades()
         if not free_open_trades:
-            return None
+            return 0
 
         available_amount = self._get_available_stake_amount()
 
         return available_amount / free_open_trades
 
-    def _check_available_stake_amount(self, stake_amount: Optional[float]) -> Optional[float]:
+    def _check_available_stake_amount(self, stake_amount: float) -> float:
         """
         Check if stake amount can be fulfilled with the available balance
         for the stake currency
@@ -307,7 +308,7 @@ class FreqtradeBot:
         """
         available_amount = self._get_available_stake_amount()
 
-        if stake_amount is not None and available_amount < stake_amount:
+        if available_amount < stake_amount:
             raise DependencyException(
                 f"Available balance ({available_amount} {self.config['stake_currency']}) is "
                 f"lower than stake amount ({stake_amount} {self.config['stake_currency']})"

tests/test_freqtradebot.py

@@ -189,13 +189,13 @@ def test_get_trade_stake_amount_unlimited_amount(default_conf, ticker, balance_r
     freqtrade.execute_buy('LTC/BTC', result)
 
     result = freqtrade.get_trade_stake_amount('XRP/BTC')
-    assert result is None
+    assert result == 0
 
     # set max_open_trades = None, so do not trade
     conf['max_open_trades'] = 0
     freqtrade = FreqtradeBot(conf)
     result = freqtrade.get_trade_stake_amount('NEO/BTC')
-    assert result is None
+    assert result == 0
 
 
 def test_edge_called_in_process(mocker, edge_conf) -> None:
@@ -576,7 +576,7 @@ def test_create_trade_limit_reached(default_conf, ticker, limit_buy_order,
     patch_get_signal(freqtrade)
 
     assert not freqtrade.create_trade('ETH/BTC')
-    assert freqtrade.get_trade_stake_amount('ETH/BTC') is None
+    assert freqtrade.get_trade_stake_amount('ETH/BTC') == 0
 
 
 def test_enter_positions_no_pairs_left(default_conf, ticker, limit_buy_order, fee,