test/vpp_ip.py: Correct usage of 'is'

* Correct 'is' (identity) usage where equality is needed '=='.
  * Change raise 'Exception' to log message and return NotImplemented.
    (see: https://docs.python.org/3/library/constants.html#NotImplemented)
  * Remove duplicate property: bytes.
  * Remove duplicate method: __eq__.

Change-Id: Id3ae4f92f985eb7cef334e2679f19ecc971007c1
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

test/vpp_ip.py

@@ -2,11 +2,14 @@
   IP Types
 
 """
+import logging
 
 from ipaddress import ip_address
 from socket import AF_INET, AF_INET6
 from vpp_papi import VppEnum
 
+_log = logging.getLogger(__name__)
+
 
 class DpoProto:
     DPO_PROTO_IP4 = 0
@@ -26,7 +29,7 @@ class VppIpAddressUnion():
         self.ip_addr = ip_address(unicode(self.addr))
 
     def encode(self):
-        if self.version is 6:
+        if self.version == 6:
             return {'ip6': self.ip_addr.packed}
         else:
             return {'ip4': self.ip_addr.packed}
@@ -41,10 +44,7 @@ class VppIpAddressUnion():
 
     @property
     def length(self):
-        if self.version is 6:
-            return 128
-        else:
-            return 32
+        return self.ip_addr.max_prefixlen
 
     @property
     def bytes(self):
@@ -55,16 +55,15 @@ class VppIpAddressUnion():
             return self.ip_addr == other.ip_addr
         elif hasattr(other, "ip4") and hasattr(other, "ip6"):
             # vl_api_address_union_t
-            if 4 is self.version:
+            if 4 == self.version:
                 return self.ip_addr.packed == other.ip4
             else:
                 return self.ip_addr.packed == other.ip6
         else:
-            raise Exception("Comparing VppIpAddresUnions:%s"
-                            " with unknown type: %s" %
-                            (self, other))
-
-        return False
+            _log.error("Comparing VppIpAddressUnions:%s"
+                       " with incomparable type: %s",
+                       self, other)
+            return NotImplemented
 
 
 class VppIpAddress():
@@ -72,7 +71,7 @@ class VppIpAddress():
         self.addr = VppIpAddressUnion(addr)
 
     def encode(self):
-        if self.addr.version is 6:
+        if self.addr.version == 6:
             return {
                 'af': VppEnum.vl_api_address_family_t.ADDRESS_IP6,
                 'un': self.addr.encode()
@@ -88,7 +87,7 @@ class VppIpAddress():
             return self.addr == other.addr
         elif hasattr(other, "af") and hasattr(other, "un"):
             # a vp_api_address_t
-            if 4 is self.version:
+            if 4 == self.version:
                 return other.af == \
                     VppEnum.vl_api_address_family_t.ADDRESS_IP4 and \
                     other.un == self.addr
@@ -97,9 +96,12 @@ class VppIpAddress():
                     VppEnum.vl_api_address_family_t.ADDRESS_IP6 and \
                     other.un == self.addr
         else:
-            raise Exception("Comparing VppIpAddress:%s with unknown type: %s" %
-                            (self, other))
-        return False
+            _log.error(
+                "Comparing VppIpAddress:<%s> %s with incomparable "
+                "type: <%s> %s",
+                self.__class__.__name__, self,
+                other.__class__.__name__, other)
+            return NotImplemented
 
     def __ne__(self, other):
         return not (self == other)
@@ -111,10 +113,6 @@ class VppIpAddress():
     def bytes(self):
         return self.addr.bytes
 
-    @property
-    def bytes(self):
-        return self.addr.bytes
-
     @property
     def address(self):
         return self.addr.address
@@ -140,7 +138,7 @@ class VppIpAddress():
 
     @property
     def dpo_proto(self):
-        if self.version is 6:
+        if self.version == 6:
             return DpoProto.DPO_PROTO_IP6
         else:
             return DpoProto.DPO_PROTO_IP4
@@ -151,11 +149,6 @@ class VppIpPrefix():
         self.addr = VppIpAddress(addr)
         self.len = len
 
-    def __eq__(self, other):
-        if self.addr == other.addr and self.len == other.len:
-            return True
-        return False
-
     def encode(self):
         return {'address': self.addr.encode(),
                 'address_length': self.len}
@@ -185,11 +178,12 @@ class VppIpPrefix():
         elif hasattr(other, "address") and hasattr(other, "address_length"):
             # vl_api_prefix_t
             return self.len == other.address_length and \
-                self.addr == other.address
+                   self.addr == other.address
         else:
-            raise Exception("Comparing VppIpPrefix:%s with unknown type: %s" %
-                            (self, other))
-        return False
+            _log.error(
+                "Comparing VppIpPrefix:%s with incomparable type: %s" %
+                (self, other))
+            return NotImplemented
 
 
 class VppIpMPrefix():
@@ -199,10 +193,12 @@ class VppIpMPrefix():
         self.len = len
         self.ip_saddr = ip_address(unicode(self.saddr))
         self.ip_gaddr = ip_address(unicode(self.gaddr))
+        if self.ip_saddr.version != self.ip_gaddr.version:
+            raise ValueError('Source and group addresses must be of the '
+                             'same address family.')
 
     def encode(self):
-
-        if 6 is self.ip_saddr.version:
+        if 6 == self.ip_saddr.version:
             prefix = {
                 'af': VppEnum.vl_api_address_family_t.ADDRESS_IP6,
                 'grp_address': {'ip6': self.ip_gaddr.packed},