py3: fix recursion issue under py37

Add tox target and resolve issue with infinite recursion in
ExtraProperties class by directly using methods on the dict
class.

Closes-Bug: 1800601

Change-Id: Ie98c4287c8bd1c364655adb99c7a88d1d451496e

glance/domain/__init__.py

@@ -300,9 +300,9 @@ class ExtraProperties(collections.MutableMapping, dict):
 
     def __eq__(self, other):
         if isinstance(other, ExtraProperties):
-            return dict(self).__eq__(dict(other))
+            return dict.__eq__(self, dict(other))
         elif isinstance(other, dict):
-            return dict(self).__eq__(other)
+            return dict.__eq__(self, other)
         else:
             return False
 
@@ -310,10 +310,10 @@ class ExtraProperties(collections.MutableMapping, dict):
         return not self.__eq__(other)
 
     def __len__(self):
-        return dict(self).__len__()
+        return dict.__len__(self)
 
     def keys(self):
-        return dict(self).keys()
+        return dict.keys(self)
 
 
 class ImageMembership(object):

tox.ini

@@ -34,6 +34,10 @@ commands = ostestr --slowest {posargs}
 basepython = python3.5
 commands = ostestr --slowest {posargs}
 
+[testenv:py37]
+basepython = python3.7
+commands = ostestr --slowest {posargs}
+
 [testenv:functional]
 setenv =
   TEST_PATH = ./glance/tests/functional
@@ -51,6 +55,16 @@ whitelist_externals =
 commands =
   stestr run --blacklist-file ./broken-functional-py35-ssl-tests.txt {posargs}
 
+[testenv:functional-py37]
+basepython = python3.7
+setenv =
+  TEST_PATH = ./glance/tests/functional
+ignore_errors = True
+whitelist_externals =
+  bash
+commands =
+  stestr run --blacklist-file ./broken-functional-py35-ssl-tests.txt {posargs}
+
 [testenv:broken-py35-ssl-tests]
 # NOTE(rosmaita): these tests were being skipped due to bug #1482633, but we
 # want it to be obvious that Glance is affected by the eventlet ssl-handshake