Allow rounding with opposite method

modules/currency/CHANGELOG

@@ -1,3 +1,5 @@
+* Allow rounding with opposite method
+
 Version 6.6.0 - 2022-10-31
 --------------------------
 * Bug fixes (see mercurial logs for details)

modules/currency/currency.py

@@ -1,8 +1,9 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 import datetime
+import decimal
 import logging
-from decimal import ROUND_HALF_EVEN, Decimal, localcontext
+from decimal import Decimal, localcontext
 
 from dateutil.relativedelta import relativedelta
 from sql import Window
@@ -24,6 +25,17 @@ from .ir import rate_decimal
 logger = logging.getLogger(__name__)
 
 
+ROUNDING_OPPOSITES = {
+    decimal.ROUND_HALF_EVEN: decimal.ROUND_HALF_EVEN,
+    decimal.ROUND_HALF_UP: decimal.ROUND_HALF_DOWN,
+    decimal.ROUND_HALF_DOWN: decimal.ROUND_HALF_UP,
+    decimal.ROUND_UP: decimal.ROUND_DOWN,
+    decimal.ROUND_DOWN: decimal.ROUND_UP,
+    decimal.ROUND_CEILING: decimal.ROUND_FLOOR,
+    decimal.ROUND_FLOOR: decimal.ROUND_CEILING,
+    }
+
+
 class Currency(
         SymbolMixin, DigitsMixin, DeactivableMixin, ModelSQL, ModelView):
     'Currency'
@@ -148,8 +160,10 @@ class Currency(
                 res[currency_id] = id2rate[res[currency_id]].rate
         return res
 
-    def round(self, amount, rounding=ROUND_HALF_EVEN):
+    def round(self, amount, rounding=decimal.ROUND_HALF_EVEN, opposite=False):
         'Round the amount depending of the currency'
+        if opposite:
+            rounding = ROUNDING_OPPOSITES[rounding]
         return self._round(amount, self.rounding, rounding)
 
     @classmethod

modules/currency/tests/test_module.py

@@ -3,7 +3,7 @@
 
 import datetime
 import unittest
-from decimal import Decimal
+from decimal import ROUND_HALF_DOWN, Decimal
 
 from trytond import backend
 from trytond.modules.currency.ecb import (
@@ -143,6 +143,29 @@ class CurrencyTestCase(ModuleTestCase):
 
         self.assertEqual(rounded, Decimal('1.2345'))
 
+    @with_transaction()
+    def test_round_opposite(self):
+        "Test the opposite rounding"
+        cu = create_currency('cu')
+        cu.save()
+
+        rounded = cu.round(Decimal('1.235'))
+        self.assertEqual(rounded, Decimal('1.24'))
+        opposite_rounded = cu.round(Decimal('1.235'), opposite=True)
+        self.assertEqual(opposite_rounded, Decimal('1.24'))
+
+    @with_transaction()
+    def test_round_opposite_HALF_DOWN(self):
+        "Test the oposite rounding of ROUND_HALF_DOWN"
+        cu = create_currency('cu')
+        cu.save()
+
+        rounded = cu.round(Decimal('1.235'), rounding=ROUND_HALF_DOWN)
+        self.assertEqual(rounded, Decimal('1.23'))
+        opposite_rounded = cu.round(
+            Decimal('1.235'), rounding=ROUND_HALF_DOWN, opposite=True)
+        self.assertEqual(opposite_rounded, Decimal('1.24'))
+
     @with_transaction()
     def test_is_zero(self):
         "Test is zero"