Add test for reference field referring unknown target

trytond/trytond/tests/test_field_reference.py

@@ -117,6 +117,18 @@ class FieldReferenceTestCase(TestCase):
 
         self.assertEqual(reference.reference, 'test.reference.target,-1')
 
+    @with_transaction()
+    def test_create_unknown(self):
+        "Test create unknown reference"
+        pool = Pool()
+        Reference = pool.get('test.reference')
+
+        reference, = Reference.create([{
+                    'reference': 'test.reference.target,48',
+                    }])
+
+        self.assertEqual(reference.reference, None)
+
     @with_transaction()
     def test_search_equals_string(self):
         "Test search reference equals string"