Issue 14814: Correctly return NotImplemented from ipaddress._BaseNetwork.__eq__

2 files changed, 22 insertions, 7 deletions

diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index e788c0a5..b1e07fc 100644
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -651,12 +651,12 @@ class _BaseNetwork(_IPAddressBase):
         return not lt
 
     def __eq__(self, other):
-        if not isinstance(other, _BaseNetwork):
-            raise TypeError('%s and %s are not of the same type' % (
-                             self, other))
-        return (self._version == other._version and
-                self.network_address == other.network_address and
-                int(self.netmask) == int(other.netmask))
+        try:
+            return (self._version == other._version and
+                    self.network_address == other.network_address and
+                    int(self.netmask) == int(other.netmask))
+        except AttributeError:
+            return NotImplemented
 
     def __ne__(self, other):
         eq = self.__eq__(other)
diff --git a/Lib/test/test_ipaddress.py b/Lib/test/test_ipaddress.py
index 2ac37e1..417c986 100644
--- a/Lib/test/test_ipaddress.py
+++ b/Lib/test/test_ipaddress.py
@@ -462,7 +462,6 @@ class IpaddrUnitTest(unittest.TestCase):
         self.assertEqual(128, ipaddress._count_righthand_zero_bits(0, 128))
         self.assertEqual("IPv4Network('1.2.3.0/24')", repr(self.ipv4_network))
         self.assertEqual('0x1020318', hex(self.ipv4_network))
-        self.assertRaises(TypeError, self.ipv4_network.__eq__, object())
 
     def testMissingAddressVersion(self):
         class Broken(ipaddress._BaseAddress):
@@ -496,6 +495,22 @@ class IpaddrUnitTest(unittest.TestCase):
         self.assertEqual(str(self.ipv6_network.hostmask),
                          '::ffff:ffff:ffff:ffff')
 
+    def testEqualityChecks(self):
+        # __eq__ should never raise TypeError directly
+        other = object()
+        def assertEqualityNotImplemented(instance):
+            self.assertEqual(instance.__eq__(other), NotImplemented)
+            self.assertEqual(instance.__ne__(other), NotImplemented)
+            self.assertFalse(instance == other)
+            self.assertTrue(instance != other)
+
+        assertEqualityNotImplemented(self.ipv4_address)
+        assertEqualityNotImplemented(self.ipv4_network)
+        assertEqualityNotImplemented(self.ipv4_interface)
+        assertEqualityNotImplemented(self.ipv6_address)
+        assertEqualityNotImplemented(self.ipv6_network)
+        assertEqualityNotImplemented(self.ipv6_interface)
+
     def testBadVersionComparison(self):
         # These should always raise TypeError
         v4addr = ipaddress.ip_address('1.1.1.1')