[FIX] base: amount_to_text possible difference

In 79038055 amount_to_text was refactored and improved, but there is a
drawback.

ie. if we have .29 cents with two decimals, `Twenty-Eight` was displayed
because `int(0.29 * 100) == 28` due to floating-point representation.

This commit keeps the improvements and fix this issue by using string
formatting of float as was done before.

opw-1829924
closes #24161

odoo/addons/base/res/res_currency.py

@@ -101,17 +101,20 @@ class Currency(models.Model):
             logging.getLogger(__name__).warning("The library 'num2words' is missing, cannot render textual amounts.")
             return ""
 
-        fractional_value, integer_value = math.modf(amount)
-        fractional_amount = round(abs(fractional_value), self.decimal_places) * (math.pow(10, self.decimal_places))
+        formatted = "%.{0}f".format(self.decimal_places) % amount
+        parts = formatted.partition('.')
+        integer_value = int(parts[0])
+        fractional_value = int(parts[2] or 0)
+
         lang_code = self.env.context.get('lang') or self.env.user.lang
         lang = self.env['res.lang'].search([('code', '=', lang_code)])
         amount_words = tools.ustr('{amt_value} {amt_word}').format(
-                        amt_value=_num2words(int(integer_value), lang=lang.iso_code),
+                        amt_value=_num2words(integer_value, lang=lang.iso_code),
                         amt_word=self.currency_unit_label,
                         )
-        if not self.is_zero(fractional_value):
+        if not self.is_zero(amount - integer_value):
             amount_words += ' ' + _('and') + tools.ustr(' {amt_value} {amt_word}').format(
-                        amt_value=_num2words(int(fractional_amount), lang=lang.iso_code),
+                        amt_value=_num2words(fractional_value, lang=lang.iso_code),
                         amt_word=self.currency_subunit_label,
                         )
         return amount_words

odoo/addons/base/tests/test_float.py

@@ -203,3 +203,12 @@ class TestFloatPrecision(TransactionCase):
 
         with self.assertRaises(AssertionError):
             float_round(0.01, precision_digits=3, precision_rounding=0.01)
+
+    def test_amount_to_text_10(self):
+        """ verify that amount_to_text works as expected """
+        currency = self.env.ref('base.EUR')
+
+        amount_target = currency.amount_to_text(0.29)
+        amount_test = currency.amount_to_text(0.28)
+        self.assertNotEqual(amount_test, amount_target,
+                            "Amount in text should not depend on float representation")