Default to proposed stake

docs/strategy-advanced.md

@@ -523,7 +523,7 @@ class AwesomeStrategy(IStrategy):
 
 ### Stake size management
 
-It is possible to manage your risk by reducing or increasing or reducing stake amount when placing a new trade.
+It is possible to manage your risk by reducing or increasing stake amount when placing a new trade.
 
 ```python
 class AwesomeStrategy(IStrategy):
@@ -546,8 +546,10 @@ class AwesomeStrategy(IStrategy):
         return proposed_stake
 ```
 
+Freqtrade will fall back to the `proposed_stake` value should your code raise an exception. The exception itself will be logged.
+
 !!! Tip
-    You do not _have_ to ensure that `min_stake <= returned_value <= max_stake`. Trades will succeed, as returned value will be clamped to supported range and this acton will be logged.
+    You do not _have_ to ensure that `min_stake <= returned_value <= max_stake`. Trades will succeed as the returned value will be clamped to supported range and this acton will be logged.
 
 !!! Tip
     Returning `0` or `None` will prevent trades from being placed.

freqtrade/freqtradebot.py

@@ -486,7 +486,7 @@ class FreqtradeBot(LoggingMixin):
         if not self.edge:
             max_stake_amount = self.wallets.get_available_stake_amount()
             stake_amount = strategy_safe_wrapper(self.strategy.custom_stake_amount,
-                                                 default_retval=None)(
+                                                 default_retval=stake_amount)(
                 pair=pair, current_time=datetime.now(timezone.utc),
                 current_rate=buy_limit_requested, proposed_stake=stake_amount,
                 min_stake=min_stake_amount, max_stake=max_stake_amount)

freqtrade/optimize/backtesting.py

@@ -319,7 +319,7 @@ class Backtesting:
         max_stake_amount = self.wallets.get_available_stake_amount()
 
         stake_amount = strategy_safe_wrapper(self.strategy.custom_stake_amount,
-                                             default_retval=None)(
+                                             default_retval=stake_amount)(
             pair=pair, current_time=row[DATE_IDX].to_pydatetime(), current_rate=row[OPEN_IDX],
             proposed_stake=stake_amount, min_stake=min_stake_amount, max_stake=max_stake_amount)
         stake_amount = self.wallets._validate_stake_amount(pair, stake_amount, min_stake_amount)

tests/optimize/test_backtesting.py

@@ -496,6 +496,17 @@ def test_backtest__enter_trade(default_conf, fee, mocker) -> None:
     trade = backtesting._enter_trade(pair, row=row)
     assert trade is not None
 
+    backtesting.strategy.custom_stake_amount = lambda **kwargs: 123.5
+    trade = backtesting._enter_trade(pair, row=row)
+    assert trade
+    assert trade.stake_amount == 123.5
+
+    # In case of error - use proposed stake
+    backtesting.strategy.custom_stake_amount = lambda **kwargs: 20 / 0
+    trade = backtesting._enter_trade(pair, row=row)
+    assert trade
+    assert trade.stake_amount == 495
+
     # Stake-amount too high!
     mocker.patch("freqtrade.exchange.Exchange.get_min_pair_stake_amount", return_value=600.0)
 

tests/test_freqtradebot.py

@@ -397,7 +397,7 @@ def test_create_trade_minimal_amount(default_conf, ticker, limit_buy_order_open,
 
 
 def test_create_trade_too_small_stake_amount(default_conf, ticker, limit_buy_order_open,
-                                             fee, mocker) -> None:
+                                             fee, mocker, caplog) -> None:
     patch_RPCManager(mocker)
     patch_exchange(mocker)
     buy_mock = MagicMock(return_value=limit_buy_order_open)
@@ -414,6 +414,7 @@ def test_create_trade_too_small_stake_amount(default_conf, ticker, limit_buy_ord
     patch_get_signal(freqtrade)
 
     assert freqtrade.create_trade('ETH/BTC')
+    assert log_has_re(r"Stake amount for pair .* is too small.*", caplog)
 
 
 def test_create_trade_zero_stake_amount(default_conf, ticker, limit_buy_order_open,
@@ -862,6 +863,24 @@ def test_execute_buy(mocker, default_conf, fee, limit_buy_order, limit_buy_order
     assert trade.open_rate == 0.5
     assert trade.stake_amount == 40.495905365
 
+    # Test with custom stake
+    limit_buy_order['status'] = 'open'
+    limit_buy_order['id'] = '556'
+
+    freqtrade.strategy.custom_stake_amount = lambda **kwargs: 150.0
+    assert freqtrade.execute_buy(pair, stake_amount)
+    trade = Trade.query.all()[4]
+    assert trade
+    assert trade.stake_amount == 150
+
+    # Exception case
+    limit_buy_order['id'] = '557'
+    freqtrade.strategy.custom_stake_amount = lambda **kwargs: 20 / 0
+    assert freqtrade.execute_buy(pair, stake_amount)
+    trade = Trade.query.all()[5]
+    assert trade
+    assert trade.stake_amount == 2.0
+
     # In case of the order is rejected and not filled at all
     limit_buy_order['status'] = 'rejected'
     limit_buy_order['amount'] = 90.99181073