diff --git a/lib/xos-genx/tests/field_graph_test.py b/lib/xos-genx/tests/field_graph_test.py
new file mode 100644
index 0000000..ea3d52d
--- /dev/null
+++ b/lib/xos-genx/tests/field_graph_test.py
@@ -0,0 +1,76 @@
+import unittest
+from xosgenx.jinja2_extensions import FieldNotFound
+from helpers import FakeArgs, OUTPUT_DIR, XProtoTestHelpers
+from xosgenx.generator import XOSGenerator
+
+class XProtoFieldGraphTest(unittest.TestCase):
+    def test_field_graph(self):
+        xproto = \
+"""
+message VRouterDevice (PlCoreBase){
+     optional string name = 1 [help_text = "device friendly name", max_length = 20, null = True, db_index = False, blank = True, unique_with="openflow_id"];
+     required string openflow_id = 2 [help_text = "device identifier in ONOS", max_length = 20, null = False, db_index = False, blank = False, unique_with="name"];
+     required string config_key = 3 [default = "basic", max_length = 32, blank = False, help_text = "configuration key", null = False, db_index = False, unique_with="driver"];
+     required string driver = 4 [help_text = "driver type", max_length = 32, null = False, db_index = False, blank = False, unique_with="vrouter_service"];
+     required manytoone vrouter_service->VRouterService:devices = 5 [db_index = True, null = False, blank = False];
+     required string A = 6 [unique_with="B"];
+     required string B = 7 [unique_with="C"];
+     required string C = 8 [unique_with="A"];
+     required string D = 9;
+     required string E = 10 [unique_with="F,G"];
+     required string F = 11;
+     required string G = 12;
+}
+"""
+	target = XProtoTestHelpers.write_tmp_target(
+"""
+{{ xproto_field_graph_components(proto.messages.0.fields) }}
+""")
+
+        args = FakeArgs()
+        args.inputs = xproto
+        args.target = target
+        output = XOSGenerator.generate(args)
+        output =  eval(output)
+        self.assertIn({'A','B','C'}, output)
+        self.assertIn({'openflow_id','name'}, output)
+        self.assertIn({'config_key','vrouter_service','driver'}, output)
+        self.assertIn({'E','F','G'}, output)
+        
+        union = reduce(lambda acc,x: acc | x, output)
+        self.assertNotIn('D', union) 
+
+    def test_missing_field(self):
+        xproto = \
+"""
+message VRouterDevice (PlCoreBase){
+     optional string name = 1 [help_text = "device friendly name", max_length = 20, null = True, db_index = False, blank = True, unique_with="hamburger"];
+     required string openflow_id = 2 [help_text = "device identifier in ONOS", max_length = 20, null = False, db_index = False, blank = False, unique_with="name"];
+     required string config_key = 3 [default = "basic", max_length = 32, blank = False, help_text = "configuration key", null = False, db_index = False, unique_with="driver"];
+     required string driver = 4 [help_text = "driver type", max_length = 32, null = False, db_index = False, blank = False, unique_with="vrouter_service"];
+     required manytoone vrouter_service->VRouterService:devices = 5 [db_index = True, null = False, blank = False];
+     required string A = 6 [unique_with="B"];
+     required string B = 7 [unique_with="C"];
+     required string C = 8 [unique_with="A"];
+     required string D = 9;
+}
+"""
+	target = XProtoTestHelpers.write_tmp_target(
+"""
+{{ xproto_field_graph_components(proto.messages.0.fields) }}
+""")
+
+        def generate():
+            args = FakeArgs()
+            args.inputs = xproto
+            args.target = target
+            output = XOSGenerator.generate(args)
+
+        # The following call generates some output, which should disappear
+        # when Matteo merges his refactoring of XOSGenerator.
+        self.assertRaises(FieldNotFound, generate)
+
+if __name__ == '__main__':
+    unittest.main()
+
+