[IMP] account: Set today as default bill date

Suppose the following workflow:
- Creates a new vendor bill.
- Set an accounting date but no bill date.
- Post the vendor bill => accounting date / bill date are set at today.

This behavior is due to the fact the user didn't set a bill date.
This commit aims to set a default bill date to encourage the user to edit it
instead of letting it empty.

addons/account/models/account_move.py

@@ -70,6 +70,10 @@ class AccountMove(models.Model):
                 raise UserError(error_msg)
         return journal
 
+    @api.model
+    def _get_default_invoice_date(self):
+        return fields.Date.today() if self._context.get('default_type', 'entry') in ('in_invoice', 'in_refund', 'in_receipt') else False
+
     @api.model
     def _get_default_currency(self):
         ''' Get the default currency from either the journal, either the default journal's company. '''
@@ -185,7 +189,8 @@ class AccountMove(models.Model):
         string='Payment', store=True, readonly=True, copy=False, tracking=True,
         compute='_compute_amount')
     invoice_date = fields.Date(string='Invoice/Bill Date', readonly=True, index=True, copy=False,
-        states={'draft': [('readonly', False)]})
+        states={'draft': [('readonly', False)]},
+        default=_get_default_invoice_date)
     invoice_date_due = fields.Date(string='Due Date', readonly=True, index=True, copy=False,
         states={'draft': [('readonly', False)]})
     invoice_payment_ref = fields.Char(string='Payment Reference', index=True, copy=False,
@@ -263,7 +268,7 @@ class AccountMove(models.Model):
     @api.onchange('invoice_date')
     def _onchange_invoice_date(self):
         if self.invoice_date:
-            if not self.invoice_date_due and not self.invoice_payment_term_id:
+            if not self.invoice_payment_term_id:
                 self.invoice_date_due = self.invoice_date
             self.date = self.invoice_date
             self._onchange_currency()

addons/account/tests/test_account_move_in_invoice.py

@@ -1172,7 +1172,7 @@ class TestAccountMoveInInvoiceOnchanges(InvoiceTestCommon):
     def test_in_invoice_duplicate_supplier_reference(self):
         ''' Ensure two vendor bills can't share the same vendor reference. '''
         self.invoice.ref = 'a supplier reference'
-        invoice2 = self.invoice.copy()
+        invoice2 = self.invoice.copy(default={'invoice_date': self.invoice.invoice_date})
 
         with self.assertRaises(ValidationError):
             invoice2.ref = 'a supplier reference'