Fix mutable default arguments in tests

Python’s default arguments are evaluated only once
when the function is defined, not each time the
function is called. This means that if you use a
mutable default argument (like list and dict) and
mutate it, you will and have mutated that object
for all future calls to the function as well.

More details about this wrong usage here:
http://docs.python-guide.org/en/latest/writing/gotchas/#mutable-default-arguments

In unit tests, most FakeXXX classes' methods take
mutable arguments with default values [] or {}.
We should change them to None.

Change-Id: Iea833b66aa1379829511ad5c6d4432b72f3488e2
Closed-bug: #1550320

Author: Tang Chen

openstackclient/tests/compute/v2/fakes.py

@@ -100,8 +100,7 @@ def create_one_aggregate(attrs=None):
         :return:
             A FakeResource object, with id and other attributes
         """
-        if attrs is None:
-            attrs = {}
+        attrs = attrs or {}
 
         # Set default attribute
         aggregate_info = {
@@ -217,14 +216,16 @@ class FakeHypervisor(object):
     """Fake one or more hypervisor."""
 
     @staticmethod
-    def create_one_hypervisor(attrs={}):
+    def create_one_hypervisor(attrs=None):
         """Create a fake hypervisor.
 
         :param Dictionary attrs:
             A dictionary with all attributes
         :return:
             A FakeResource object, with id, hypervisor_hostname, and so on
         """
+        attrs = attrs or {}
+
         # Set default attributes.
         hypervisor_info = {
             'id': 'hypervisor-id-' + uuid.uuid4().hex,
@@ -263,7 +264,7 @@ def create_one_hypervisor(attrs={}):
         return hypervisor
 
     @staticmethod
-    def create_hypervisors(attrs={}, count=2):
+    def create_hypervisors(attrs=None, count=2):
         """Create multiple fake hypervisors.
 
         :param Dictionary attrs:
@@ -284,14 +285,16 @@ class FakeHypervisorStats(object):
     """Fake one or more hypervisor stats."""
 
     @staticmethod
-    def create_one_hypervisor_stats(attrs={}):
+    def create_one_hypervisor_stats(attrs=None):
         """Create a fake hypervisor stats.
 
         :param Dictionary attrs:
             A dictionary with all attributes
         :return:
             A FakeResource object, with id, hypervisor_hostname, and so on
         """
+        attrs = attrs or {}
+
         # Set default attributes.
         stats_info = {
             'count': 2,
@@ -319,7 +322,7 @@ def create_one_hypervisor_stats(attrs={}):
         return hypervisor_stats
 
     @staticmethod
-    def create_hypervisors_stats(attrs={}, count=2):
+    def create_hypervisors_stats(attrs=None, count=2):
         """Create multiple fake hypervisors stats.
 
         :param Dictionary attrs:
@@ -349,8 +352,7 @@ def create_one_security_group(attrs=None):
         :return:
             A FakeResource object, with id, name, etc.
         """
-        if attrs is None:
-            attrs = {}
+        attrs = attrs or {}
 
         # Set default attributes.
         security_group_attrs = {
@@ -400,8 +402,7 @@ def create_one_security_group_rule(attrs=None):
         :return:
             A FakeResource object, with id, etc.
         """
-        if attrs is None:
-            attrs = {}
+        attrs = attrs or {}
 
         # Set default attributes.
         security_group_rule_attrs = {
@@ -445,7 +446,7 @@ class FakeServer(object):
     """Fake one or more compute servers."""
 
     @staticmethod
-    def create_one_server(attrs={}, methods={}):
+    def create_one_server(attrs=None, methods=None):
         """Create a fake server.
 
         :param Dictionary attrs:
@@ -455,6 +456,9 @@ def create_one_server(attrs={}, methods={}):
         :return:
             A FakeResource object, with id, name, metadata
         """
+        attrs = attrs or {}
+        methods = methods or {}
+
         # Set default attributes.
         server_info = {
             'id': 'server-id-' + uuid.uuid4().hex,
@@ -477,7 +481,7 @@ def create_one_server(attrs={}, methods={}):
         return server
 
     @staticmethod
-    def create_servers(attrs={}, methods={}, count=2):
+    def create_servers(attrs=None, methods=None, count=2):
         """Create multiple fake servers.
 
         :param Dictionary attrs:
@@ -527,8 +531,7 @@ def create_one_flavor(attrs=None):
         :return:
             A FakeResource object, with id, name, ram, vcpus, properties
         """
-        if attrs is None:
-            attrs = {}
+        attrs = attrs or {}
 
         # Set default attributes.
         flavor_info = {
@@ -566,7 +569,7 @@ def create_one_flavor(attrs=None):
         return flavor
 
     @staticmethod
-    def create_flavors(attrs={}, count=2):
+    def create_flavors(attrs=None, count=2):
         """Create multiple fake flavors.
 
         :param Dictionary attrs:
@@ -614,10 +617,9 @@ def create_one_keypair(attrs=None, no_pri=False):
         :return:
             A FakeResource
         """
-        # Set default attributes.
-        if attrs is None:
-            attrs = {}
+        attrs = attrs or {}
 
+        # Set default attributes.
         keypair_info = {
             'name': 'keypair-name-' + uuid.uuid4().hex,
             'fingerprint': 'dummy',
@@ -658,14 +660,16 @@ class FakeAvailabilityZone(object):
     """Fake one or more compute availability zones (AZs)."""
 
     @staticmethod
-    def create_one_availability_zone(attrs={}):
+    def create_one_availability_zone(attrs=None):
         """Create a fake AZ.
 
         :param Dictionary attrs:
             A dictionary with all attributes
         :return:
             A FakeResource object with zoneName, zoneState, etc.
         """
+        attrs = attrs or {}
+
         # Set default attributes.
         host_name = uuid.uuid4().hex
         service_name = uuid.uuid4().hex
@@ -689,7 +693,7 @@ def create_one_availability_zone(attrs={}):
         return availability_zone
 
     @staticmethod
-    def create_availability_zones(attrs={}, count=2):
+    def create_availability_zones(attrs=None, count=2):
         """Create multiple fake AZs.
 
         :param Dictionary attrs:
@@ -712,14 +716,16 @@ class FakeFloatingIP(object):
     """Fake one or more floating ip."""
 
     @staticmethod
-    def create_one_floating_ip(attrs={}):
+    def create_one_floating_ip(attrs=None):
         """Create a fake floating ip.
 
         :param Dictionary attrs:
             A dictionary with all attributes
         :return:
             A FakeResource object, with id, ip, and so on
         """
+        attrs = attrs or {}
+
         # Set default attributes.
         floating_ip_attrs = {
             'id': 'floating-ip-id-' + uuid.uuid4().hex,
@@ -739,7 +745,7 @@ def create_one_floating_ip(attrs={}):
         return floating_ip
 
     @staticmethod
-    def create_floating_ips(attrs={}, count=2):
+    def create_floating_ips(attrs=None, count=2):
         """Create multiple fake floating ips.
 
         :param Dictionary attrs:
@@ -778,14 +784,16 @@ class FakeNetwork(object):
     """Fake one or more networks."""
 
     @staticmethod
-    def create_one_network(attrs={}):
+    def create_one_network(attrs=None):
         """Create a fake network.
 
         :param Dictionary attrs:
             A dictionary with all attributes
         :return:
             A FakeResource object, with id, label, cidr and so on
         """
+        attrs = attrs or {}
+
         # Set default attributes.
         network_attrs = {
             'bridge': 'br100',
@@ -831,7 +839,7 @@ def create_one_network(attrs={}):
         return network
 
     @staticmethod
-    def create_networks(attrs={}, count=2):
+    def create_networks(attrs=None, count=2):
         """Create multiple fake networks.
 
         :param Dictionary attrs:
@@ -860,8 +868,7 @@ def create_one_host(attrs=None):
         :return:
             A FakeResource object, with id and other attributes
         """
-        if attrs is None:
-            attrs = {}
+        attrs = attrs or {}
 
         # Set default attributes.
         host_info = {

openstackclient/tests/fakes.py

@@ -142,7 +142,7 @@ def __init__(self, name, version):
 
 class FakeResource(object):
 
-    def __init__(self, manager=None, info={}, loaded=False, methods={}):
+    def __init__(self, manager=None, info=None, loaded=False, methods=None):
         """Set attributes and methods for a resource.
 
         :param manager:
@@ -154,6 +154,9 @@ def __init__(self, manager=None, info={}, loaded=False, methods={}):
         :param Dictionary methods:
             A dictionary with all methods
         """
+        info = info or {}
+        methods = methods or {}
+
         self.__name__ = type(self).__name__
         self.manager = manager
         self._info = info
@@ -189,9 +192,12 @@ def keys(self):
 
 class FakeResponse(requests.Response):
 
-    def __init__(self, headers={}, status_code=200, data=None, encoding=None):
+    def __init__(self, headers=None, status_code=200,
+                 data=None, encoding=None):
         super(FakeResponse, self).__init__()
 
+        headers = headers or {}
+
         self.status_code = status_code
 
         self.headers.update(headers)

openstackclient/tests/image/v2/fakes.py

@@ -181,7 +181,7 @@ class FakeImage(object):
     """
 
     @staticmethod
-    def create_one_image(attrs={}):
+    def create_one_image(attrs=None):
         """Create a fake image.
 
         :param Dictionary attrs:
@@ -190,6 +190,8 @@ def create_one_image(attrs={}):
             A FakeResource object with id, name, owner, protected,
             visibility and tags attrs
         """
+        attrs = attrs or {}
+
         # Set default attribute
         image_info = {
             'id': 'image-id' + uuid.uuid4().hex,
@@ -210,7 +212,7 @@ def create_one_image(attrs={}):
         return image
 
     @staticmethod
-    def create_images(attrs={}, count=2):
+    def create_images(attrs=None, count=2):
         """Create multiple fake images.
 
         :param Dictionary attrs: