Remove unused util function

With the recent change to federation API[0], this utility function
is no longer used. This change removes it as well as the
associated test.

[0] https://review.openstack.org/#/c/585782/

Change-Id: I69a6c6c2ed9dad7e48c11312a3b2f9a2edca9ef4

keystone/common/utils.py

@@ -119,23 +119,6 @@ def attr_as_boolean(val_attr):
     return strutils.bool_from_string(val_attr, default=True)
 
 
-def remove_duplicate_dicts_by_id(item_list):
-    """Return a list with duplicate items removed.
-
-    This compares duplicates based on item id. This is to account
-    for dictionaries of items that can contain values, such as a
-    list of tags, that will not be guaranteed to be in order.
-
-    :param item_list: a list of dictionaries
-    :returns: a list of unique dictionaries
-
-    """
-    unique = {}
-    for i in item_list:
-        unique[i['id']] = i
-    return list(unique.values())
-
-
 def auth_str_equal(provided, known):
     """Constant-time string comparison.
 

keystone/tests/unit/common/test_utils.py

@@ -71,34 +71,6 @@ class UtilsTestCase(unit.BaseTestCase):
         self.assertRaises(ValueError, common_utils.resource_uuid,
                           value)
 
-    def test_remove_duplicate_dicts_from_list(self):
-        dict_list = []
-        num_of_duplicate = 10
-        dup_value = {
-            'id': uuid.uuid4().hex,
-            'name': uuid.uuid4().hex,
-            'tags': ['foo', 'bar']
-        }
-        # Add in 10 unique items, and 10 of the same item
-        for i in range(num_of_duplicate):
-            new_dict = {
-                'id': i,
-                'name': uuid.uuid4().hex,
-                'tags': ['foo', i]
-            }
-            dict_list.append(new_dict)
-            dict_list.append(dup_value)
-        self.assertEqual(len(dict_list), 20)
-        result = common_utils.remove_duplicate_dicts_by_id(dict_list)
-        # Assert that 9 duplicate items have been removed
-        self.assertEqual(len(result), len(dict_list) - 9)
-        # Show that the duplicate item is only stored once
-        count = 0
-        for r in result:
-            if r['id'] == dup_value['id']:
-                count += 1
-        self.assertEqual(count, 1)
-
     def test_hash(self):
         password = 'right'
         wrong = 'wrongwrong'  # Two wrongs don't make a right