contract_payment_mode: Several fixes+imps:

* Copy partner payment mode to contracts when installing
* Filter payment modes for sales
* Adding tests

contract_payment_mode/hooks.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# © 2016 Antiun Ingenieria S.L. - Antonio Espinosa
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from openerp import api, SUPERUSER_ID
+import logging
+
+_logger = logging.getLogger(__name__)
+
+
+def post_init_hook(cr, registry):
+    """Copy payment mode from partner to the new field at contract."""
+    with api.Environment.manage():
+        env = api.Environment(cr, SUPERUSER_ID, {})
+        m_contract = env['account.analytic.account']
+        contracts = m_contract.search([
+            ('type', '=', 'contract'),
+            ('payment_mode_id', '=', False),
+        ])
+        if contracts:
+            _logger.info('Setting payment mode: %d contracts' %
+                         len(contracts))
+        for contract in contracts:
+            payment_mode = contract.partner_id.customer_payment_mode
+            if payment_mode:
+                contract.payment_mode_id = payment_mode.id
+        _logger.info('Setting payment mode: Done')