Simplify usage of amount_to_contract precision

freqtrade/exchange/__init__.py

@@ -9,11 +9,11 @@ from freqtrade.exchange.bitpanda import Bitpanda
 from freqtrade.exchange.bittrex import Bittrex
 from freqtrade.exchange.bybit import Bybit
 from freqtrade.exchange.coinbasepro import Coinbasepro
-from freqtrade.exchange.exchange import (amount_to_contracts, amount_to_precision,
+from freqtrade.exchange.exchange import (amount_to_contract_precision, amount_to_contracts,
-                                         available_exchanges, ccxt_exchanges, contracts_to_amount,
+                                         amount_to_precision, available_exchanges, ccxt_exchanges,
-                                         date_minus_candles, is_exchange_known_ccxt,
+                                         contracts_to_amount, date_minus_candles,
-                                         is_exchange_officially_supported, market_is_active,
+                                         is_exchange_known_ccxt, is_exchange_officially_supported,
-                                         price_to_precision, timeframe_to_minutes,
+                                         market_is_active, price_to_precision, timeframe_to_minutes,
                                          timeframe_to_msecs, timeframe_to_next_date,
                                          timeframe_to_prev_date, timeframe_to_seconds,
                                          validate_exchange, validate_exchanges)

freqtrade/exchange/exchange.py

@@ -2943,6 +2943,29 @@ def amount_to_precision(amount: float, amount_precision: Optional[float],
     return amount
 
 
+def amount_to_contract_precision(
+        amount, amount_precision: Optional[float], precisionMode: Optional[int],
+        contract_size: Optional[float]) -> float:
+    """
+    Returns the amount to buy or sell to a precision the Exchange accepts
+    including calculation to and from contracts.
+    Re-implementation of ccxt internal methods - ensuring we can test the result is correct
+    based on our definitions.
+    :param amount: amount to truncate
+    :param amount_precision: amount precision to use.
+                             should be retrieved from markets[pair]['precision']['amount']
+    :param precisionMode: precision mode to use. Should be used from precisionMode
+                          one of ccxt's DECIMAL_PLACES, SIGNIFICANT_DIGITS, or TICK_SIZE
+    :param contract_size: contract size - taken from exchange.get_contract_size(pair)
+    :return: truncated amount
+    """
+    if amount_precision is not None and precisionMode is not None:
+        contracts = amount_to_contracts(amount, contract_size)
+        amount_p = amount_to_precision(contracts, amount_precision, precisionMode)
+        return contracts_to_amount(amount_p, contract_size)
+    return amount
+
+
 def price_to_precision(price: float, price_precision: Optional[float],
                        precisionMode: Optional[int]) -> float:
     """

freqtrade/optimize/backtesting.py

@@ -23,9 +23,8 @@ from freqtrade.data.dataprovider import DataProvider
 from freqtrade.enums import (BacktestState, CandleType, ExitCheckTuple, ExitType, RunMode,
                              TradingMode)
 from freqtrade.exceptions import DependencyException, OperationalException
-from freqtrade.exchange import timeframe_to_minutes, timeframe_to_seconds
+from freqtrade.exchange import (amount_to_contract_precision, price_to_precision,
-from freqtrade.exchange.exchange import (amount_to_contracts, amount_to_precision,
+                                timeframe_to_minutes, timeframe_to_seconds)
-                                         contracts_to_amount, price_to_precision)
 from freqtrade.mixins import LoggingMixin
 from freqtrade.optimize.backtest_caching import get_strategy_run_id
 from freqtrade.optimize.bt_progress import BTProgress
@@ -659,11 +658,8 @@ class Backtesting:
         exit_candle_time = sell_row[DATE_IDX].to_pydatetime()
         order_type = self.strategy.order_types['exit']
         # amount = amount or trade.amount
-        amount = contracts_to_amount(
+        amount = amount_to_contract_precision(amount or trade.amount, trade.amount_precision,
-                amount_to_precision(
+                                              self.precision_mode, trade.contract_size)
-                    amount_to_contracts(amount or trade.amount, trade.contract_size),
-                    trade.amount_precision, self.precision_mode),
-                trade.contract_size)
         rate = price_to_precision(close_rate, trade.price_precision, self.precision_mode)
         order = Order(
             id=self.order_id_counter,
@@ -835,10 +831,7 @@ class Backtesting:
 
             contract_size = self.exchange.get_contract_size(pair)
             precision_amount = self.exchange.get_precision_amount(pair)
-            amount = contracts_to_amount(
+            amount = amount_to_contract_precision(amount_p, precision_amount, self.precision_mode,
-                amount_to_precision(
-                    amount_to_contracts(amount_p, contract_size),
-                    precision_amount, self.precision_mode),
                                                   contract_size)
             # Backcalculate actual stake amount.
             stake_amount = amount * propose_rate / leverage

freqtrade/persistence/trade_model.py

@@ -14,8 +14,7 @@ from freqtrade.constants import (DATETIME_PRINT_FORMAT, MATH_CLOSE_PREC, NON_OPE
                                  BuySell, LongShort)
 from freqtrade.enums import ExitType, TradingMode
 from freqtrade.exceptions import DependencyException, OperationalException
-from freqtrade.exchange import amount_to_precision, price_to_precision
+from freqtrade.exchange import amount_to_contract_precision, price_to_precision
-from freqtrade.exchange.exchange import amount_to_contracts, contracts_to_amount
 from freqtrade.leverage import interest
 from freqtrade.persistence.base import _DECL_BASE
 from freqtrade.util import FtPrecise
@@ -625,11 +624,8 @@ class LocalTrade():
             else:
                 logger.warning(
                     f'Got different open_order_id {self.open_order_id} != {order.order_id}')
-            amount_tr = contracts_to_amount(
+            amount_tr = amount_to_contract_precision(self.amount, self.amount_precision,
-                amount_to_precision(
+                                                     self.precision_mode, self.contract_size)
-                    amount_to_contracts(self.amount, self.contract_size),
-                    self.amount_precision, self.precision_mode),
-                self.contract_size)
             if isclose(order.safe_amount_after_fee, amount_tr, abs_tol=MATH_CLOSE_PREC):
                 self.close(order.safe_price)
             else:
@@ -882,8 +878,8 @@ class LocalTrade():
             self.realized_profit = close_profit_abs
             self.close_profit_abs = profit
 
-        current_amount_tr = amount_to_precision(float(current_amount),
+        current_amount_tr = amount_to_contract_precision(
-                                                self.amount_precision, self.precision_mode)
+            float(current_amount), self.amount_precision, self.precision_mode, self.contract_size)
         if current_amount_tr > 0.0:
             # Trade is still open
             # Leverage not updated, as we don't allow changing leverage through DCA at the moment.

tests/optimize/test_backtesting_adjust_position.py

@@ -18,7 +18,8 @@ from tests.conftest import patch_exchange
 def test_backtest_position_adjustment(default_conf, fee, mocker, testdatadir) -> None:
     default_conf['use_exit_signal'] = False
     mocker.patch('freqtrade.exchange.Exchange.get_fee', fee)
-    mocker.patch('freqtrade.optimize.backtesting.amount_to_precision', lambda x, y, z: round(x, 8))
+    mocker.patch('freqtrade.optimize.backtesting.amount_to_contract_precision',
+                 lambda x, *args, **kwargs: round(x, 8))
     mocker.patch("freqtrade.exchange.Exchange.get_min_pair_stake_amount", return_value=0.00001)
     mocker.patch("freqtrade.exchange.Exchange.get_max_pair_stake_amount", return_value=float('inf'))
     patch_exchange(mocker)