Fix unit test error

1. What is the problem
Unit tests fail due to miss function of update_fields.

2. What is the solution for the problem
Add update_fields function.

3. What features need to be implemented to the Tricircle to
realize the solution
N/A

Change-Id: I41bff60b4c4cffb1eddde9e2733c4ebaa9ad948c

tricircle/tests/unit/utils.py

@@ -107,6 +107,9 @@ class DotDict(dict):
             return dummy_value_map[item]
         return self.get(item)
 
+    def __setattr__(self, name, value):
+        self[name] = value
+
     def to_dict(self):
         return self
 
@@ -119,6 +122,11 @@ class DotDict(dict):
     def save(self, session=None):
         pass
 
+    def update_fields(self, obj_data):
+        for k, v in obj_data.items():
+            if k in self:
+                setattr(self, k, v)
+
 
 class DotList(list):
     def all(self):