[ADD] contract_variable_quantity:

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Variable quantity in contract recurrent invoicing
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With this module, you will be able to define in recurring contracts some
lines with variable quantity according a provided formula.

Configuration
=============

* Go to Sales > Configuration > Contracts > Formulas (quantity).
* Define any formula based on Python code that stores at some moment a
  float/integer value of the quantity to invoice in the variable 'result'.

  You can use these variables to compute your formula:

  * *env*: Environment variable for getting other models.
  * *context*: Current context dictionary.
  * *user*: Current user.
  * *line*: Contract recurring invoice line that triggers this formula.
  * *contract*: Contract whose line belongs to.
  * *invoice*: Invoice (header) being created.

Usage
=====

To use this module, you need to:

* Go to Sales -> Contracts and select or create a new contract.
* Check *Generate recurring invoices automatically*.
* Add a new recurring invoicing line.
* Select "Variable quantity" in column "Qty. type".
* Select one of the possible formulas to use (previously created).

contract_variable_quantity/tests/__init__.py

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from . import test_contract_variable_quantity

contract_variable_quantity/tests/test_contract_variable_quantity.py

@@ -0,0 +1,60 @@
+# -*- coding: utf-8 -*-
+# © 2016 Pedro M. Baeza <pedro.baeza@tecnativa.com>
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from openerp.tests import common
+from openerp import exceptions
+
+
+class TestContractVariableQuantity(common.SavepointCase):
+    @classmethod
+    def setUpClass(cls):
+        super(TestContractVariableQuantity, cls).setUpClass()
+        cls.partner = cls.env['res.partner'].create({
+            'name': 'Test partner',
+        })
+        cls.product = cls.env['product.product'].create({
+            'name': 'Test product',
+        })
+        cls.contract = cls.env['account.analytic.account'].create({
+            'name': 'Test Contract',
+            'partner_id': cls.partner.id,
+            'pricelist_id': cls.partner.property_product_pricelist.id,
+            'recurring_invoices': True,
+        })
+        cls.formula = cls.env['contract.line.qty.formula'].create({
+            'name': 'Test formula',
+            # For testing each of the possible variables
+            'code': 'env["res.users"]\n'
+                    'context.get("lang")\n'
+                    'user.id\n'
+                    'line.qty_type\n'
+                    'contract.id\n'
+                    'invoice.id\n'
+                    'result = 12',
+        })
+        cls.contract_line = cls.env['account.analytic.invoice.line'].create({
+            'analytic_account_id': cls.contract.id,
+            'product_id': cls.product.id,
+            'name': 'Test',
+            'qty_type': 'variable',
+            'qty_formula_id': cls.formula.id,
+            'quantity': 1,
+            'uom_id': cls.product.uom_id.id,
+            'price_unit': 100,
+            'discount': 50,
+        })
+
+    def test_check_invalid_code(self):
+        with self.assertRaises(exceptions.ValidationError):
+            self.formula.code = "sdsds"
+
+    def test_check_no_return_value(self):
+        with self.assertRaises(exceptions.ValidationError):
+            self.formula.code = "user.id"
+
+    def test_check_variable_quantity(self):
+        self.contract._create_invoice(self.contract)
+        invoice = self.env['account.invoice'].search(
+            [('contract_id', '=', self.contract.id)])
+        self.assertEqual(invoice.invoice_line_ids[0].quantity, 12)