[FIX] account: unreconcile payment

- Company currency in EUR
- Create 2 rates for USD:
  1.0 on 2018-01-01
  0.5 on 2018-02-01
- Create an invoice on 2018-01-02 of 111 USD
- Register a payment on 2018-02-02 of 111 USD
- Unreconcile the payment

An error occurs: 'You are trying to reconcile some entries that are
already reconciled!'

In this specific case where the rate decreases, the exchange rate entry
is reconciled with the payment, so we need to keep the payment entries.

2 files changed, 50 insertions, 1 deletions

diff --git a/addons/account/models/account_move.py b/addons/account/models/account_move.py
index 727bdf298ae..fe5e0564e30 100644
--- a/addons/account/models/account_move.py
+++ b/addons/account/models/account_move.py
@@ -1175,8 +1175,9 @@ class AccountMoveLine(models.Model):
             rec_move_ids += account_move_line.matched_credit_ids
         if self.env.context.get('invoice_id'):
             current_invoice = self.env['account.invoice'].browse(self.env.context['invoice_id'])
+            aml_to_keep = current_invoice.move_id.line_ids | current_invoice.move_id.line_ids.mapped('full_reconcile_id.exchange_move_id.line_ids')
             rec_move_ids = rec_move_ids.filtered(
-                lambda r: (r.debit_move_id + r.credit_move_id) & current_invoice.move_id.line_ids
+                lambda r: (r.debit_move_id + r.credit_move_id) & aml_to_keep
             )
         return rec_move_ids.unlink()
 
diff --git a/addons/account/tests/test_reconciliation.py b/addons/account/tests/test_reconciliation.py
index 84c8092234b..286e623c0da 100644
--- a/addons/account/tests/test_reconciliation.py
+++ b/addons/account/tests/test_reconciliation.py
@@ -657,3 +657,51 @@ class TestReconciliation(AccountingTestCase):
         credit_aml.with_context(invoice_id=inv2.id).remove_move_reconcile()
         self.assertAlmostEquals(inv1.residual, 10)
         self.assertAlmostEquals(inv2.residual, 20)
+
+    def test_unreconcile_exchange(self):
+        # Use case:
+        # - Company currency in EUR
+        # - Create 2 rates for USD:
+        #   1.0 on 2018-01-01
+        #   0.5 on 2018-02-01
+        # - Create an invoice on 2018-01-02 of 111 USD
+        # - Register a payment on 2018-02-02 of 111 USD
+        # - Unreconcile the payment
+
+        self.env['res.currency.rate'].create({
+            'name': time.strftime('%Y') + '-07-01',
+            'rate': 1.0,
+            'currency_id': self.currency_usd_id,
+            'company_id': self.env.ref('base.main_company').id
+        })
+        self.env['res.currency.rate'].create({
+            'name': time.strftime('%Y') + '-08-01',
+            'rate': 0.5,
+            'currency_id': self.currency_usd_id,
+            'company_id': self.env.ref('base.main_company').id
+        })
+        inv = self.create_invoice(invoice_amount=111, currency_id=self.currency_usd_id)
+        payment = self.env['account.payment'].create({
+            'payment_type': 'inbound',
+            'payment_method_id': self.env.ref('account.account_payment_method_manual_in').id,
+            'partner_type': 'customer',
+            'partner_id': self.partner_agrolait_id,
+            'amount': 111,
+            'currency_id': self.currency_usd_id,
+            'journal_id': self.bank_journal_usd.id,
+            'payment_date': time.strftime('%Y') + '-08-01',
+        })
+        payment.post()
+        credit_aml = payment.move_line_ids.filtered('credit')
+
+        # Check residual before assignation
+        self.assertAlmostEquals(inv.residual, 111)
+
+        # Assign credit, check exchange move and residual
+        inv.assign_outstanding_credit(credit_aml.id)
+        self.assertEqual(len(payment.move_line_ids.mapped('full_reconcile_id').exchange_move_id), 1)
+        self.assertAlmostEquals(inv.residual, 0)
+
+        # Unreconcile invoice and check residual
+        credit_aml.with_context(invoice_id=inv.id).remove_move_reconcile()
+        self.assertAlmostEquals(inv.residual, 111)