Support non-dict mappings in mask_dict_password

mask_dict_password doesn't actually have a dependency on the dict
type specifically. It can work on any subclass of collections.Mapping.
This changes the isinstance check to reflect that and adds a unit
test using a collections.Mapping subclass.

Change-Id: I28781acf027b9b34f8274196db5dd4d2a9adc9ba
Closes-Bug: 1804528

oslo_utils/strutils.py

@@ -17,6 +17,7 @@
 System-level utilities and helper functions.
 """
 
+import collections
 import math
 import re
 import unicodedata
@@ -390,12 +391,12 @@ def mask_dict_password(dictionary, secret="***"):  # nosec
 
     """
 
-    if not isinstance(dictionary, dict):
-        raise TypeError("Expected a dictionary, got %s instead."
+    if not isinstance(dictionary, collections.Mapping):
+        raise TypeError("Expected a Mapping, got %s instead."
                         % type(dictionary))
     out = {}
     for k, v in dictionary.items():
-        if isinstance(v, dict):
+        if isinstance(v, collections.Mapping):
             out[k] = mask_dict_password(v, secret=secret)
             continue
         # NOTE(jlvillal): Check to see if anything in the dictionary 'key'

oslo_utils/tests/test_strutils.py

@@ -15,6 +15,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import collections
 import copy
 import math
 
@@ -613,6 +614,31 @@ class MaskPasswordTestCase(test_base.BaseTestCase):
         self.assertEqual(expected, strutils.mask_password(payload))
 
 
+class TestMapping(collections.Mapping):
+    """Test class for non-dict mappings"""
+    def __init__(self):
+        super(TestMapping, self).__init__()
+        self.data = {'password': 'shhh',
+                     'foo': 'bar',
+                     }
+
+    def __getitem__(self, key):
+        return self.data[key]
+
+    def __iter__(self):
+        return self.data.__iter__()
+
+    def __len__(self):
+        return len(self.data)
+
+
+class NestedMapping(TestMapping):
+    """Test class that contains an instance of TestMapping"""
+    def __init__(self):
+        super(NestedMapping, self).__init__()
+        self.data = {'nested': TestMapping()}
+
+
 class MaskDictionaryPasswordTestCase(test_base.BaseTestCase):
 
     def test_dictionary(self):
@@ -696,6 +722,21 @@ class MaskDictionaryPasswordTestCase(test_base.BaseTestCase):
         strutils.mask_dict_password(payload)
         self.assertEqual(pristine, payload)
 
+    def test_non_dict(self):
+        expected = {'password': '***',
+                    'foo': 'bar',
+                    }
+        payload = TestMapping()
+        self.assertEqual(expected, strutils.mask_dict_password(payload))
+
+    def test_nested_non_dict(self):
+        expected = {'nested': {'password': '***',
+                               'foo': 'bar',
+                               }
+                    }
+        payload = NestedMapping()
+        self.assertEqual(expected, strutils.mask_dict_password(payload))
+
 
 class IsIntLikeTestCase(test_base.BaseTestCase):
     def test_is_int_like_true(self):