__metaclass__ as class level, adapt test to new version

sale.py

@@ -6,7 +6,6 @@ from trytond.pool import Pool, PoolMeta
 from trytond.modules.product import price_digits
 
 __all__ = ['SaleLine', 'Purchase', 'PurchaseLine']
-__metaclass__ = PoolMeta
 
 _QUANTIZE = Decimal(str(10 ** -price_digits[1]))
 _CONFIRMED_STATES = ('confirmed', 'processing', 'done')
@@ -14,6 +13,7 @@ _CONFIRMED_STATES = ('confirmed', 'processing', 'done')
 
 class SaleLine:
     __name__ = 'sale.line'
+    __metaclass__ = PoolMeta
 
     @classmethod
     def update_cost_price(cls, lines):
@@ -64,6 +64,7 @@ class SaleLine:
 
 class Purchase:
     __name__ = 'purchase.purchase'
+    __metaclass__ = PoolMeta
 
     @classmethod
     def cancel(cls, purchases):
@@ -86,6 +87,7 @@ class Purchase:
 
 class PurchaseLine:
     __name__ = 'purchase.line'
+    __metaclass__ = PoolMeta
 
     @classmethod
     def create(cls, vlist):

tests/__init__.py

@@ -1,3 +1,8 @@
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
-from .test_sale_opportunity_purchase_relation_margin import suite
+try:
+    from trytond.modules.sale.tests.test_sale_opportunity_purchase_relation_margin import suite
+except ImportError:
+    from .test_sale_opportunity_purchase_relation_margin import suite
+
+__all__ = ['suite']

tests/test_sale_opportunity_purchase_relation_margin.py

@@ -3,20 +3,13 @@
 import unittest
 import doctest
 import trytond.tests.test_tryton
-from trytond.tests.test_tryton import test_depends
-from trytond.tests.test_tryton import doctest_setup, doctest_teardown
+from trytond.tests.test_tryton import ModuleTestCase
+from trytond.tests.test_tryton import (doctest_setup, doctest_teardown,
+    doctest_checker)
 
-
-class TestCase(unittest.TestCase):
-    'Test module'
-
-    def setUp(self):
-        trytond.tests.test_tryton.install_module(
-            'sale_opportunity_purchase_relation_margin')
-
-    def test0006depends(self):
-        'Test depends'
-        test_depends()
+class TestCase(ModuleTestCase):
+    'Test Sale Opportunity Purchase Relation Margin'
+    module = 'sale_opportunity_purchase_relation_margin'
 
 
 def suite():
@@ -25,5 +18,6 @@ def suite():
     suite.addTests(doctest.DocFileSuite(
             'scenario_sale_opportunity_purchase_relation_margin.rst',
             setUp=doctest_setup, tearDown=doctest_teardown, encoding='utf-8',
-            optionflags=doctest.REPORT_ONLY_FIRST_FAILURE))
+            optionflags=doctest.REPORT_ONLY_FIRST_FAILURE,
+            checker=doctest_checker))
     return suite