[IMP] account: don't always allow modifying the decimal places of a currency

If accounting entries have already been generated by this currency, we now forbid setting it a lesser number of decimal places (so, higher rounding factor). We also display a warning when increasing the number of decimal places, to make sure the user is aware of the impact it'll have.

closes odoo/odoo#42017

Signed-off-by: Laurent Smet <smetl@users.noreply.github.com>

addons/account/__manifest__.py

@@ -63,6 +63,7 @@ You could use this simplified accounting in case you work with an (external) acc
         'views/account_tax_report_views.xml',
         'report/account_hash_integrity_templates.xml',
         'wizard/account_transfer_wizard.xml',
+        'views/res_currency.xml',
     ],
     'demo': [
         'demo/account_demo.xml',

addons/account/models/__init__.py

@@ -21,3 +21,4 @@ from . import account_incoterms
 from . import digest
 from . import res_users
 from . import ir_actions_report
+from . import res_currency

addons/account/models/res_currency.py

@@ -0,0 +1,37 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import api, models, fields, _
+
+from odoo.exceptions import UserError
+
+
+class ResCurrency(models.Model):
+    _inherit = 'res.currency'
+
+    display_rounding_warning = fields.Boolean(string="Display Rounding Warning", compute='_compute_display_rounding_warning', help="Technical field used to tell whether or not to display the warning informing a rounding factor change might be dangerous on res.currency's form view.")
+
+
+    @api.depends('rounding')
+    def _compute_display_rounding_warning(self):
+        for record in self:
+            record.display_rounding_warning = record._origin.rounding != record.rounding \
+                                              and record._origin._has_accounting_entries()
+
+    def write(self, vals):
+        if 'rounding' in vals:
+            rounding_val = vals['rounding']
+            for record in self:
+                if (rounding_val > record.rounding or rounding_val == 0) and record._has_accounting_entries():
+                    raise UserError(_("You cannot reduce the number of decimal places of a currency which has already been used to make accounting entries. If you really need to do that, please contact tech support."))
+
+        return super(ResCurrency, self).write(vals)
+
+    def _has_accounting_entries(self):
+        """ Returns True iff this currency has been used to generate (hence, round)
+        some move lines (either as their foreign currency, or as the main currency
+        of their company).
+        """
+        self.ensure_one()
+        return bool(self.env['account.move.line'].search_count(['|', ('currency_id', '=', self.id), ('company_currency_id', '=', self.id)]))
+

addons/account/tests/test_tax.py

@@ -1,46 +1,52 @@
 # -*- coding: utf-8 -*-
-from odoo.addons.account.tests.common import AccountTestUsersCommon
+from odoo.addons.account.tests.common import AccountTestInvoicingCommon
 from odoo.tests import tagged
 
 
 @tagged('post_install', '-at_install')
-class TestTaxCommon(AccountTestUsersCommon):
+class TestTaxCommon(AccountTestInvoicingCommon):
 
     @classmethod
     def setUpClass(cls):
         super(TestTaxCommon, cls).setUpClass()
 
-        cls.fixed_tax = cls.tax_model.create({
+        # Setup another company having a rounding of 1.0.
+        cls.currency_data['currency'].rounding = 1.0
+        cls.currency_no_decimal = cls.currency_data['currency']
+        cls.company_data_2 = cls.setup_company_data('company_2', currency_id=cls.currency_no_decimal.id)
+        cls.env.user.company_id = cls.company_data['company']
+
+        cls.fixed_tax = cls.env['account.tax'].create({
             'name': "Fixed tax",
             'amount_type': 'fixed',
             'amount': 10,
             'sequence': 1,
         })
-        cls.fixed_tax_bis = cls.tax_model.create({
+        cls.fixed_tax_bis = cls.env['account.tax'].create({
             'name': "Fixed tax bis",
             'amount_type': 'fixed',
             'amount': 15,
             'sequence': 2,
         })
-        cls.percent_tax = cls.tax_model.create({
+        cls.percent_tax = cls.env['account.tax'].create({
             'name': "Percent tax",
             'amount_type': 'percent',
             'amount': 10,
             'sequence': 3,
         })
-        cls.percent_tax_bis = cls.tax_model.create({
+        cls.percent_tax_bis = cls.env['account.tax'].create({
             'name': "Percent tax bis",
             'amount_type': 'percent',
             'amount': 10,
             'sequence': 4,
         })
-        cls.division_tax = cls.tax_model.create({
+        cls.division_tax = cls.env['account.tax'].create({
             'name': "Division tax",
             'amount_type': 'division',
             'amount': 10,
             'sequence': 4,
         })
-        cls.group_tax = cls.tax_model.create({
+        cls.group_tax = cls.env['account.tax'].create({
             'name': "Group tax",
             'amount_type': 'group',
             'amount': 0,
@@ -50,7 +56,7 @@ class TestTaxCommon(AccountTestUsersCommon):
                 (4, cls.percent_tax.id, 0)
             ]
         })
-        cls.group_tax_bis = cls.tax_model.create({
+        cls.group_tax_bis = cls.env['account.tax'].create({
             'name': "Group tax bis",
             'amount_type': 'group',
             'amount': 0,
@@ -60,7 +66,7 @@ class TestTaxCommon(AccountTestUsersCommon):
                 (4, cls.percent_tax.id, 0)
             ]
         })
-        cls.group_of_group_tax = cls.tax_model.create({
+        cls.group_of_group_tax = cls.env['account.tax'].create({
             'name': "Group of group tax",
             'amount_type': 'group',
             'amount': 0,
@@ -70,14 +76,14 @@ class TestTaxCommon(AccountTestUsersCommon):
                 (4, cls.group_tax_bis.id, 0)
             ]
         })
-        cls.tax_with_no_account = cls.tax_model.create({
+        cls.tax_with_no_account = cls.env['account.tax'].create({
             'name': "Tax with no account",
             'amount_type': 'fixed',
             'amount': 0,
             'sequence': 8,
         })
         some_account = cls.env['account.account'].search([], limit=1)
-        cls.tax_with_account = cls.tax_model.create({
+        cls.tax_with_account = cls.env['account.tax'].create({
             'name': "Tax with account",
             'amount_type': 'fixed',
             'amount': 0,
@@ -108,15 +114,15 @@ class TestTaxCommon(AccountTestUsersCommon):
             ],
         })
 
-        cls.tax_19_percent = cls.tax_model.create({
+        cls.tax_19_percent = cls.env['account.tax'].with_company(cls.company_data_2['company']).create({
             'name': "test_rounding_methods_1",
             'amount_type': 'percent',
             'amount': 19,
         })
 
-        cls.bank_journal = cls.env['account.journal'].search([('type', '=', 'bank'), ('company_id', '=', cls.account_manager.company_id.id)])[0]
+        cls.bank_journal = cls.company_data['default_journal_bank']
         cls.bank_account = cls.bank_journal.default_debit_account_id
-        cls.expense_account = cls.env['account.account'].search([('user_type_id.type', '=', 'payable')], limit=1) #Should be done by onchange later
+        cls.expense_account = cls.company_data['default_account_expense']
 
     def _check_compute_all_results(self, total_included, total_excluded, taxes, res):
         self.assertAlmostEqual(res['total_included'], total_included)
@@ -662,7 +668,6 @@ class TestTax(TestTaxCommon):
         The decimal precision is set to zero.
         The computation must be similar to round(22689 * 0.19) + round(9176 * 0.19).
         '''
-        self.tax_19_percent.company_id.currency_id.rounding = 1.0
         self.tax_19_percent.company_id.tax_calculation_rounding_method = 'round_per_line'
 
         res1 = self.tax_19_percent.compute_all(22689)
@@ -696,7 +701,6 @@ class TestTax(TestTaxCommon):
         The decimal precision is set to zero.
         The computation must be similar to round((22689 + 9176) * 0.19).
         '''
-        self.tax_19_percent.company_id.currency_id.rounding = 1.0
         self.tax_19_percent.company_id.tax_calculation_rounding_method = 'round_globally'
 
         res1 = self.tax_19_percent.compute_all(22689)
@@ -731,7 +735,6 @@ class TestTax(TestTaxCommon):
         The computation must be similar to round(27000 / 1.19) + round(10920 / 1.19).
         '''
         self.tax_19_percent.price_include = True
-        self.tax_19_percent.company_id.currency_id.rounding = 1.0
         self.tax_19_percent.company_id.tax_calculation_rounding_method = 'round_per_line'
 
         res1 = self.tax_19_percent.compute_all(27000)
@@ -766,7 +769,6 @@ class TestTax(TestTaxCommon):
         The computation must be similar to round((27000 + 10920) / 1.19).
         '''
         self.tax_19_percent.price_include = True
-        self.tax_19_percent.company_id.currency_id.rounding = 1.0
         self.tax_19_percent.company_id.tax_calculation_rounding_method = 'round_globally'
 
         res1 = self.tax_19_percent.compute_all(27000)

addons/account/views/res_currency.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+    <data>
+
+        <record id="res_currency_form_inherit" model="ir.ui.view">
+            <field name="name">res.currency.form.inherit</field>
+            <field name="model">res.currency</field>
+            <field name="inherit_id" ref="base.view_currency_form"/>
+            <field name="arch" type="xml">
+                <xpath expr="//sheet" position="before">
+                    <field name="display_rounding_warning" invisible="1"/>
+                    <div class="alert alert-warning" role="alert" attrs="{'invisible': [('display_rounding_warning', '=', False)]}">
+                        <strong>This currency has already been used to generate accounting entries.</strong> <br/>
+                        Changing its rounding factor now will not change the rounding made on previous entries; possibly causing an inconsistency with the new ones.
+                    </div>
+                </xpath>
+            </field>
+        </record>
+
+    </data>
+</odoo>

addons/account_tax_python/tests/test_tax.py

@@ -9,7 +9,7 @@ class TestTaxPython(TestTaxCommon):
     @classmethod
     def setUpClass(cls):
         super(TestTaxPython, cls).setUpClass()
-        cls.python_tax = cls.tax_model.create({
+        cls.python_tax = cls.env['account.tax'].create({
             'name': 'Python TAx',
             'amount_type': 'code',
             'amount': 0.0,