Re-enables the TCP test for the DNS chain functions (Closes: #172)

Ensure you're using python3-libtrace with Debian package version
>= 1.6+git20170608-1

pathspider/tests/test_chain_dns.py

@@ -19,24 +19,21 @@ def test_chain_dns_valid_response(self):
         for key in expected_dns:
             assert flows[0][key] == expected_dns[key]
 
-# Temporarily disabled https://github.com/mami-project/pathspider/issues/172
-############################################################################
-#    def test_chain_dns_valid_response_tcp(self):
-#        test_trace = "dns_valid_response_tcp.pcap"
-#        self.create_observer(test_trace, [DNSChain])
-#
-#        expected_dns = {
-#            'dns_response_valid': True,
-#        }
-#
-#        flows = self.run_observer()
-#        assert len(flows) == 1
-#
-#        print(flows)
-#
-#        for key in expected_dns:
-#            assert flows[0][key] == expected_dns[key]
-############################################################################
+    def test_chain_dns_valid_response_tcp(self):
+        test_trace = "dns_valid_response_tcp.pcap"
+        self.create_observer(test_trace, [DNSChain])
+
+        expected_dns = {
+            'dns_response_valid': True,
+        }
+
+        flows = self.run_observer()
+        assert len(flows) == 1
+
+        print(flows)
+
+        for key in expected_dns:
+            assert flows[0][key] == expected_dns[key]
 
     def test_chain_dns_no_response(self):
         test_trace = "dns_no_response.pcap"