add resolver tests

dns/cache.py

@@ -123,8 +123,11 @@ class RecordCache(object):
 
     def read_cache_file(self):
         """ Read the cache file from disk """
-        with open("cache.json") as f:
-            self.records = json.load(f, object_hook=resource_from_json)
+        try:
+            with open("cache.json") as f:
+                self.records = json.load(f, object_hook=resource_from_json)
+        except Exception, e:
+            print "error loading cache", repr(e)
         self.sweep()
     def write_cache_file(self):
         """ Write the cache file to disk """

dns/resolver.py

@@ -45,7 +45,6 @@ class Resolver(object):
         self.SBELT.read_master_file("named.root")
         if caching:
             self.cache = dns.cache.RecordCache(self.ttl)
-            self.cache.read_cache_file()
         else:
             self.cache = dns.cache.DummyCache(self.ttl)
 

dns_client.py

@@ -20,6 +20,7 @@ if __name__ == "__main__":
     
     # Resolve hostname
     resolver = dns.resolver.Resolver(args.caching, args.ttl)
+    resolver.cache.read_cache_file()
     hostname, aliases, addresses = resolver.gethostbyname(args.hostname)
     resolver.cache.write_cache_file()
     # Print output

dns_tests.py

@@ -5,12 +5,49 @@
 portnr = 5353
 server = "localhost"
 
+import dns.resolver
+from dns.resource import ResourceRecord, RecordData
+from dns.classes import Class
+from dns.types import Type
+import unittest
+import sys
+import time
+
 class TestResolver(unittest.TestCase):
-    pass
+    # solve a FQDN, output with corresponding IP/CNAME/authoitative status generated
+    def test_solve(self):
+        resolver = dns.resolver.Resolver(False, 0)
+        host, alias, ip = resolver.gethostbyname("mail.polvanaubel.com")
+        self.assertEqual(host, "sog.polvanaubel.com")
+        self.assertEqual(alias, ["sog.polvanaubel.com"])
+        self.assertEqual(ip, ["138.201.39.104"])
+    def test_invalid(self):
+        resolver = dns.resolver.Resolver(False, 0)
+        host, alias, ip = resolver.gethostbyname("invalid.example.com")
+        self.assertFalse(host)
+        self.assertFalse(alias)
+        self.assertFalse(ip)
 
 
 class TestResolverCache(unittest.TestCase):
-    pass
+    # solve an invalid cached FQDN, output corresponds to cache
+    def test_solveinv(self):
+        resolver = dns.resolver.Resolver(True, 0)
+        resolver.cache.add_record(ResourceRecord("invalid.example.com", Type.A, Class.IN, 60, RecordData("1.2.3.4")))
+        host, alias, ip = resolver.gethostbyname("invalid.example.com")
+        self.assertEqual(host, "invalid.example.com")
+        self.assertEqual(alias, [])
+        self.assertEqual(ip, ["1.2.3.4"])
+    # start your server and wait configured TTL + 1 time for an invalid cached FQDN to expire,
+    # an empty output should be generated
+    def test_ttlexpire(self):
+        resolver = dns.resolver.Resolver(True, 0.05)
+        resolver.cache.add_record(ResourceRecord("invalid.example.com", Type.A, Class.IN, 60, RecordData("1.2.3.4")))
+        time.sleep(0.06)
+        host, alias, ip = resolver.gethostbyname("invalid.example.com")
+        self.assertFalse(host)
+        self.assertFalse(alias)
+        self.assertFalse(ip)
 
 
 class TestServer(unittest.TestCase):