[OpenWrt] Fixed empty dns and dns-search bug

netjsonconfig/backends/openwrt/renderers.py

@@ -165,14 +165,12 @@ def _get_ip_rules(self):
     def __get_dns_servers(self):
         dns = self.config.get('dns_servers', None)
         if dns:
-            dns = ' '.join(dns)
-        return dns
+            return ' '.join(dns)
 
     def __get_dns_search(self):
-        dns = self.config.get('dns_search', None)
-        if dns:
-            dns = ' '.join(dns)
-        return dns
+        dns_search = self.config.get('dns_search', None)
+        if dns_search:
+            return ' '.join(dns_search)
 
     def _get_switches(self):
         uci_switches = []

tests/openwrt/test_network.py

@@ -827,5 +827,24 @@ def test_ula_prefix(self):
 
 config globals 'globals'
     option ula_prefix 'fd8e:f40a:6701::/48'
+""")
+        self.assertEqual(o.render(), expected)
+
+    def test_empty_dns(self):
+        o = OpenWrt({
+            "interfaces": [
+                {
+                    "name": "eth0",
+                    "type": "ethernet"
+                }
+            ],
+            "dns_servers": [],
+            "dns_search": []
+        })
+        expected = self._tabs("""package network
+
+config interface 'eth0'
+    option ifname 'eth0'
+    option proto 'none'
 """)
         self.assertEqual(o.render(), expected)