pythongh-130607: Extend and cleanup IPv6 tests (pythonGH-121518)

Extend IPv6 tests and made little syntax refactoring
(cherry picked from commit 9f0879b)

Co-authored-by: Ilya Bazhenov <31971067+bazhil@users.noreply.github.com>

Author: bazhil

Lib/test/test_ipaddress.py

@@ -886,8 +886,8 @@ class ComparisonTests(unittest.TestCase):
     v6net = ipaddress.IPv6Network(1)
     v6intf = ipaddress.IPv6Interface(1)
     v6addr_scoped = ipaddress.IPv6Address('::1%scope')
-    v6net_scoped= ipaddress.IPv6Network('::1%scope')
-    v6intf_scoped= ipaddress.IPv6Interface('::1%scope')
+    v6net_scoped = ipaddress.IPv6Network('::1%scope')
+    v6intf_scoped = ipaddress.IPv6Interface('::1%scope')
 
     v4_addresses = [v4addr, v4intf]
     v4_objects = v4_addresses + [v4net]
@@ -1075,6 +1075,7 @@ def setUp(self):
         self.ipv6_scoped_interface = ipaddress.IPv6Interface(
             '2001:658:22a:cafe:200:0:0:1%scope/64')
         self.ipv6_scoped_network = ipaddress.IPv6Network('2001:658:22a:cafe::%scope/64')
+        self.ipv6_with_ipv4_part = ipaddress.IPv6Interface('::1.2.3.4')
 
     def testRepr(self):
         self.assertEqual("IPv4Interface('1.2.3.4/32')",
@@ -1694,6 +1695,8 @@ def testEqual(self):
 
         self.assertTrue(self.ipv6_scoped_interface ==
             ipaddress.IPv6Interface('2001:658:22a:cafe:200::1%scope/64'))
+        self.assertTrue(self.ipv6_with_ipv4_part ==
+            ipaddress.IPv6Interface('0000:0000:0000:0000:0000:0000:0102:0304'))
         self.assertFalse(self.ipv6_scoped_interface ==
             ipaddress.IPv6Interface('2001:658:22a:cafe:200::1%scope/63'))
         self.assertFalse(self.ipv6_scoped_interface ==
@@ -2173,6 +2176,7 @@ def testIPVersion(self):
         self.assertEqual(self.ipv4_address.version, 4)
         self.assertEqual(self.ipv6_address.version, 6)
         self.assertEqual(self.ipv6_scoped_address.version, 6)
+        self.assertEqual(self.ipv6_with_ipv4_part.version, 6)
 
     def testMaxPrefixLength(self):
         self.assertEqual(self.ipv4_interface.max_prefixlen, 32)