Fix error in resource_help and add UT

The func should be used in the condition of 'policies to policy'
Add test UT in test_resource_helper

Change-Id: I41fa8b0b029398ea9c3977fabd649a094a9538ac

tacker/api/v1/resource_helper.py

@@ -30,7 +30,12 @@ def build_plural_mappings(special_mappings, resource_map):
     """
     plural_mappings = {}
     for plural in resource_map:
-        singular = special_mappings.get(plural, plural[:-1])
+        singular = special_mappings.get(plural)
+        if not singular:
+            if plural.endswith('ies'):
+                singular = "%sy" % plural[:-3]
+            else:
+                singular = plural[:-1]
         plural_mappings[plural] = singular
     return plural_mappings
 

tacker/tests/unit/api/v1/test_resource_helper.py

@@ -0,0 +1,61 @@
+# Copyright (c) 2014-2018 China Mobile (SuZhou) Software Technology Co.,Ltd.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from tacker.api.v1.resource_helper import build_plural_mappings
+from tacker.tests import base
+
+
+class ResourceHelperTestCase(base.BaseTestCase):
+
+    def test_build_plural_mappings(self):
+        special_mappings = {}
+        resource_map = {
+            'vims': {
+                'id': {
+                    'allow_post': False,
+                    'allow_put': False,
+                }
+            },
+            'vnffgs': {
+                'id': {
+                    'allow_post': False,
+                    'allow_put': False,
+                }
+            },
+        }
+
+        expected_res = {'vnffgs': 'vnffg', 'vims': 'vim'}
+        result = build_plural_mappings(special_mappings, resource_map)
+        self.assertEqual(expected_res, result)
+
+    def test_build_plural_mappings_with_suffix_y(self):
+        special_mappings = {}
+        resource_map = {
+            'policies': {
+                'id': {
+                    'allow_post': False,
+                }
+            },
+            'vnffgs': {
+                'id': {
+                    'allow_post': False,
+                    'allow_put': False,
+                }
+            },
+        }
+
+        expected_res = {'vnffgs': 'vnffg', 'policies': 'policy'}
+        result = build_plural_mappings(special_mappings, resource_map)
+        self.assertEqual(expected_res, result)