[FIX] account: tax base computation

Before the fix, the tax base amount is computed only for a complete
invoice line. However, depending on the tax sequence and their inclusion
in the base amount, the tax base amount might be different for the
various taxes of an invoice line.

We keep track of the base amount for every single tax, and refactor the
`_compute_base_amount` to take these values into account.

opw-691177
Closes #13819

addons/account/models/account.py

@@ -717,6 +717,9 @@ class AccountTax(models.Model):
             else:
                 total_included += tax_amount
 
+            # Keep base amount used for the current tax
+            tax_base = base
+
             if tax.include_base_amount:
                 base += tax_amount
 
@@ -724,6 +727,7 @@ class AccountTax(models.Model):
                 'id': tax.id,
                 'name': tax.with_context(**{'lang': partner.lang} if partner else {}).name,
                 'amount': tax_amount,
+                'base': tax_base,
                 'sequence': tax.sequence,
                 'account_id': tax.account_id.id,
                 'refund_account_id': tax.refund_account_id.id,

addons/account/models/account_invoice.py

@@ -12,6 +12,9 @@ from openerp.tools.misc import formatLang
 from openerp.exceptions import UserError, RedirectWarning, ValidationError
 
 import openerp.addons.decimal_precision as dp
+import logging
+
+_logger = logging.getLogger(__name__)
 
 # mapping invoice type to journal type
 TYPE2JOURNAL = {
@@ -551,6 +554,7 @@ class AccountInvoice(models.Model):
             'name': tax['name'],
             'tax_id': tax['id'],
             'amount': tax['amount'],
+            'base': tax['base'],
             'manual': False,
             'sequence': tax['sequence'],
             'account_analytic_id': tax['analytic'] and line.account_analytic_id.id or False,
@@ -580,6 +584,7 @@ class AccountInvoice(models.Model):
                     tax_grouped[key] = val
                 else:
                     tax_grouped[key]['amount'] += val['amount']
+                    tax_grouped[key]['base'] += val['base']
         return tax_grouped
 
     @api.multi
@@ -1293,15 +1298,19 @@ class AccountInvoiceTax(models.Model):
     _order = 'sequence'
 
     def _compute_base_amount(self):
+        tax_grouped = {}
+        for invoice in self.mapped('invoice_id'):
+            tax_grouped[invoice.id] = invoice.get_taxes_values()
         for tax in self:
-            base = 0.0
-            for line in tax.invoice_id.invoice_line_ids:
-                if tax.tax_id in line.invoice_line_tax_ids:
-                    price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-                    base += (line.invoice_line_tax_ids - tax.tax_id).compute_all(
-                        price_unit, line.invoice_id.currency_id, line.quantity, line.product_id, line.invoice_id.partner_id
-                    )['base']
-            tax.base = base
+            key = self.env['account.tax'].browse(tax.tax_id.id).get_grouping_key({
+                'tax_id': tax.tax_id.id,
+                'account_id': tax.account_id.id,
+                'account_analytic_id': tax.account_analytic_id.id,
+            })
+            if tax.invoice_id and key in tax_grouped[tax.invoice_id.id]:
+                tax.base = tax_grouped[tax.invoice_id.id][key]['base']
+            else:
+                _logger.warning('Tax Base Amount not computable probably due to a change in an underlying tax (%s).', tax.tax_id.name)
 
     invoice_id = fields.Many2one('account.invoice', string='Invoice', ondelete='cascade', index=True)
     name = fields.Char(string='Tax Description', required=True)

addons/account/tests/test_account_supplier_invoice.py

@@ -41,3 +41,65 @@ class TestAccountSupplierInvoice(AccountingTestCase):
         #I cancel the account move which is in posted state and verifies that it gives warning message
         with self.assertRaises(Warning):
             invoice.move_id.button_cancel()
+
+    def test_supplier_invoice2(self):
+        tax_fixed = self.env['account.tax'].create({
+            'sequence': 10,
+            'name': 'Tax 10.0 (Fixed)',
+            'amount': 10.0,
+            'amount_type': 'fixed',
+            'include_base_amount': True,
+        })
+        tax_percent_included_base_incl = self.env['account.tax'].create({
+            'sequence': 20,
+            'name': 'Tax 50.0% (Percentage of Price Tax Included)',
+            'amount': 50.0,
+            'amount_type': 'division',
+            'include_base_amount': True,
+        })
+        tax_percentage = self.env['account.tax'].create({
+            'sequence': 30,
+            'name': 'Tax 20.0% (Percentage of Price)',
+            'amount': 20.0,
+            'amount_type': 'percent',
+            'include_base_amount': False,
+        })
+        analytic_account = self.env['account.analytic.account'].create({
+            'name': 'test account',
+        })
+
+        # Should be changed by automatic on_change later
+        invoice_account = self.env['account.account'].search([('user_type_id', '=', self.env.ref('account.data_account_type_receivable').id)], limit=1).id
+        invoice_line_account = self.env['account.account'].search([('user_type_id', '=', self.env.ref('account.data_account_type_expenses').id)], limit=1).id
+
+        invoice = self.env['account.invoice'].create({'partner_id': self.env.ref('base.res_partner_2').id,
+            'account_id': invoice_account,
+            'type': 'in_invoice',
+        })
+
+        invoice_line = self.env['account.invoice.line'].create({'product_id': self.env.ref('product.product_product_4').id,
+            'quantity': 5.0,
+            'price_unit': 100.0,
+            'invoice_id': invoice.id,
+            'name': 'product that cost 100',
+            'account_id': invoice_line_account,
+            'invoice_line_tax_ids': [(6, 0, [tax_fixed.id, tax_percent_included_base_incl.id, tax_percentage.id])],
+            'account_analytic_id': analytic_account.id,
+        })
+        invoice.compute_taxes()
+
+        # check that Initially supplier bill state is "Draft"
+        self.assertTrue((invoice.state == 'draft'), "Initially vendor bill state is Draft")
+
+        #change the state of invoice to open by clicking Validate button
+        invoice.signal_workflow('invoice_open')
+
+        # Check if amount and corresponded base is correct for all tax scenarios given on a computational base
+        # Keep in mind that tax amount can be changed by the user at any time before validating (based on the invoice and tax laws applicable)
+        invoice_tax = invoice.tax_line_ids.sorted(key=lambda r: r.sequence)
+        self.assertEquals(invoice_tax.mapped('amount'), [50.0, 550.0, 220.0])
+        self.assertEquals(invoice_tax.mapped('base'), [500.0, 550.0, 1100.0])
+
+        #I cancel the account move which is in posted state and verifies that it gives warning message
+        with self.assertRaises(Warning):
+            invoice.move_id.button_cancel()