added metaclass interface for response

restler/engine/transport_layer/response.py

@@ -1,5 +1,6 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
+from abc import ABCMeta, abstractmethod, abstractproperty
 import string
 import re
 from typing import Dict, List
@@ -17,15 +18,62 @@
 # of a sequence because the sequence failed prior to that request being reached.
 RESTLER_INVALID_CODE = '999'
 
-class Http2Response(object):
+class AbstractHttpResponse(object, metaclass=ABCMeta):
+    @abstractmethod
+    def __init__(self, response):
+        pass
+
+    @abstractproperty
+    def to_str(self):
+        pass
+
+    @abstractproperty
+    def to_str(self) -> str:
+        pass
+
+    @abstractproperty
+    def status_code(self) -> str:
+        pass
+
+    @abstractproperty
+    def body(self) -> str:
+        pass
+
+    @abstractproperty
+    def headers(self) -> str:
+        """Raw response header section of response"""
+        pass
+
+    @abstractproperty
+    def headers_list(self) -> Dict:
+        pass
+
+    @abstractmethod
+    def has_valid_code(self) -> bool:
+        pass
+
+    @abstractmethod
+    def has_bug_code(self) -> bool:
+        pass
+
+    @abstractproperty
+    def json_body(self) -> str:
+        pass
+
+    @abstractproperty
+    def status_text(self) -> str:
+        pass
+
+
+class Http2Response(AbstractHttpResponse):
     def __init__(self, response: hyper.HTTP20Response):
         """ Hyper response facade
         """
         self._response = response
         self._body = self._response.read(decode_content=True).decode('utf-8')
 
     @property
-    def to_str(self):
+    def to_str(self) -> str:
         #TODO: remove the need for this function.
         # It is hacky.
         return f"{self.headers}{DELIM}{self.body}"
@@ -75,7 +123,7 @@ def status_text(self) -> str:
         return ""
 
 
-class HttpResponse(object):
+class HttpResponse(AbstractHttpResponse):
     def __init__(self, response_str: str=None):
         """ Initializes an HttpResponse object