Fix interfaces unique names checking on dnsmasq (#38)

debinterface/dnsmasqRange.py

@@ -76,16 +76,18 @@ def validate(self):
                         raise ValueError("Missing option : {0}".format(key))
                 if inet_aton(rng["end"]) < inet_aton(rng["start"]):
                     raise ValueError("Start IP range must be before end IP")
-                return True
+
             itf_names = [
                 data["interface"]
                 for data in self._config["dhcp-range"]
             ]
-            if len(itf_names) != set(itf_names):
+
+            if len(itf_names) != len(set(itf_names)):
                 msg = "Multiple interfaces with the same name"
                 raise ValueError(msg)
         except KeyError:
             pass  # dhcp-range is not mandatory
+        return True
 
     def update_range(self, interface, start, end, lease_time):
         """Update existing range based on the interface name

test/test_dnsmasqRange.py

@@ -128,3 +128,13 @@ def test_update_range(self):
         self.assertEqual(set(expected.keys()), set(cur_range.keys()))
         for expected_key, expected_value in expected.items():
             self.assertEqual(expected_value, cur_range[expected_key])
+
+    def test_validate_invalid_duplicate_interface(self):
+        """Test validate with duplicate interface name"""
+
+        dns = DnsmasqRange("fdlkfdl")
+        invalid = copy.deepcopy(DNSMASQ_DEFAULT_CONFIG)
+        invalid["dhcp-range"][1]["interface"] = invalid["dhcp-range"][0]["interface"]
+        dns._config = invalid
+        with self.assertRaises(ValueError):
+            dns.validate()