New error handling in poc and features

poc/bin/kapow

@@ -178,14 +178,14 @@ async def get_field(request):
     try:
         connection = CONNECTIONS[id]
     except KeyError:
-        response = web.Response(status=404, reason="Handler ID Not Found")
+        response = web.json_response(data=error_body("Handler ID Not Found"), status=404, reason="Not Found")
     else:
         try:
             content = await connection.get(field)
         except ValueError:
-            return web.Response(status=400, reason="Invalid Resource Path")
+            return web.json_response(data=error_body("Invalid Resource Path"), status=400, reason="Bad Request")
         except KeyError:
-            return web.Response(status=404, reason="Resource Item Not Found")
+            return web.json_response(data=error_body("Resource Item Not Found"), status=404, reason="Not Found")
 
         if isinstance(content, StreamReader):
             response = web.StreamResponse(status=200, reason="OK")
@@ -210,8 +210,10 @@ async def set_field(request):
 
     try:
         connection = CONNECTIONS[id]
+    except ValueError:
+        return web.json_response(data=error_body("Invalid Resource Path"), status=400, reason="Bad Request")
     except KeyError:
-        response = web.Response(status=404, reason="Handler ID Not Found")
+        response = web.json_response(data=error_body("Handler ID Not Found"), status=404, reason="Not Found")
     else:
         try:
             await connection.set(field, request.content)
@@ -275,6 +277,9 @@ def handle_route(entrypoint, command):
 ########################################################################
 
 
+def error_body(reason):
+    return {"reason": reason}
+
 def get_routes(app):
     async def _get_routes(request):
         """Return the list of registered routes."""
@@ -302,7 +307,7 @@ def get_route(app):
                                           "entrypoint": r.entrypoint,
                                           "command": r.command})
         else:
-            return web.Response(status=404, reason="Not Found")
+            return web.json_response(data=error_body("Route Not Found"), status=404, reason="Not Found")
     return _get_route
 
 
@@ -312,7 +317,7 @@ def insert_route(app):
         try:
             content = await request.json()
         except ValueError:
-            return web.Response(status=400, reason="Malformed JSON")
+            return web.json_response(data=error_body("Malformed JSON"), status=400, reason="Bad Request")
 
         try:
             index = int(content["index"])
@@ -330,7 +335,7 @@ def insert_route(app):
                                + [route]
                                + app["user_routes"][index:]))
         except (InvalidRouteError, KeyError, AssertionError, ValueError) as exc:
-            return web.Response(status=422, reason="Invalid Route")
+            return web.json_response(data=error_body("Invalid Route"), status=422, reason="Unprocessable Entity")
         else:
             app["user_routes"].insert(index, route)
             return web.json_response({"id": route.id,
@@ -348,7 +353,7 @@ def append_route(app):
         try:
             content = await request.json()
         except ValueError as exc:
-            return web.Response(status=400, reason="Malformed JSON")
+            return web.json_response(data=error_body("Malformed JSON"), status=400, reason="Bad Request")
 
         try:
             method = content.get("method", "GET")
@@ -362,7 +367,7 @@ def append_route(app):
                                handler=handle_route(entrypoint, command))
             app.change_routes(app["user_routes"] + [route])
         except (InvalidRouteError, KeyError) as exc:
-            return web.Response(status=422, reason="Invalid Route")
+            return web.json_response(data=error_body("Invalid Route"), status=422, reason="Unprocessable Entity")
         else:
             app["user_routes"].append(route)
             return web.json_response({"id": route.id,
@@ -381,7 +386,7 @@ def delete_route(app):
         id = request.match_info["id"]
         routes = [r for r in app["user_routes"] if r.id != id]
         if len(routes) == len(app["user_routes"]):
-            return web.Response(status=404, reason="Not Found")
+            return web.json_response(data=error_body("Route Not Found"), status=404, reason="Not Found")
         else:
             app.change_routes(routes)
             app["user_routes"] = routes

spec/test/features/control/append/error_malformed.feature

@@ -28,4 +28,10 @@ Feature: Kapow! server reject append requests with malformed JSON bodies.
       Hi! I am an invalid JSON document.
       """
     Then I get 400 as response code
-      And I get "Malformed JSON" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Malformed JSON"
+      }
+      """

spec/test/features/control/append/error_unprocessable.feature

@@ -31,7 +31,13 @@ Feature: Kapow! server rejects requests with semantic errors.
       }
       """
     Then I get 422 as response code
-      And I get "Invalid Route" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Invalid Route"
+      }
+      """
 
   Scenario: Error because bad route format.
     If a request contains an invalid expression in the
@@ -48,4 +54,10 @@ Feature: Kapow! server rejects requests with semantic errors.
       }
       """
     Then I get 422 as response code
-      And I get "Invalid Route" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Invalid Route"
+      }
+      """

spec/test/features/control/delete/error_notfound.feature

@@ -24,4 +24,10 @@ Feature: Fail to delete a route in Kapow! server.
     Given I have a just started Kapow! server
     When I delete the route with id "xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx"
     Then I get 404 as response code
-      And I get "Not Found" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Route Not Found"
+      }
+      """

spec/test/features/control/get/error_notfound.feature

@@ -24,4 +24,10 @@ Feature: Fail to retrieve route details in Kapow! server.
     Given I have a just started Kapow! server
     When I get the route with id "xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx"
     Then I get 404 as response code
-      And I get "Not Found" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Route Not Found"
+      }
+      """

spec/test/features/control/insert/error_malformed.feature

@@ -37,4 +37,10 @@ Feature: Kapow! server rejects insertion requests with malformed JSON bodies.
       }
       """
     Then I get 400 as response code
-      And I get "Malformed JSON" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Malformed JSON"
+      }
+      """

spec/test/features/control/insert/error_unprocessable.feature

@@ -67,4 +67,10 @@ Feature: Kapow! server rejects insertion requests with semantic errors.
       }
       """
     Then I get 422 as response code
-      And I get "Invalid Route" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Invalid Route"
+      }
+      """

spec/test/features/data/handler/error_handleridnotfound.feature

@@ -25,4 +25,10 @@ Feature: Fail to retrieve resources from nonexistent handler in Kapow! server.
     Given I have a running Kapow! server
     When I get the resource "/request/path" for the handler with id "XXXXXXXXXX"
     Then I get 404 as response code
-      And I get "Handler ID Not Found" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Handler ID Not Found"
+      }
+      """

spec/test/features/data/handler/error_invalidresource.feature

@@ -27,4 +27,10 @@ Feature: Fail to retrieve an invalid resource for a handler in Kapow! server.
     When I send a request to the testing route "/foo"
       And I get the resource "/invented/path"
     Then I get 400 as response code
-      And I get "Invalid Resource Path" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Invalid Resource Path"
+      }
+      """

spec/test/features/data/handler/error_itemnotfound.feature

@@ -28,4 +28,10 @@ Feature: Fail to retrieve nonexistent resource items in Kapow! server.
     When I send a request to the testing route "/foo"
       And I get the resource "/request/params/meloinvento"
     Then I get 404 as response code
-      And I get "Resource Item Not Found" as response reason phrase
+      And the response header "Content-Type" contains "application/json"
+      And I get the following response body:
+      """
+      {
+        "reason": "Resource Item Not Found"
+      }
+      """

spec/test/features/steps/steps.py

@@ -185,6 +185,16 @@ def step_impl(context, code):
     assert context.testing_response.status_code == int(code), f"Got {context.testing_response.status_code} instead"
 
 
+@then('the response header {header_name} contains {value}')
+def step_impl(context, header_name, value):
+    assert context.response.headers.get(header_name) == value, f"Got {context.response.headers.get(header_name)} instead"
+
+
+@then('the testing response header {header_name} contains {value}')
+def step_impl(context, header_name, value):
+    assert context.testing_response.headers.get(header_name) == value, f"Got {context.testing_response.headers.get(header_name)} instead"
+
+
 @then('I get "{reason}" as response reason phrase')
 def step_impl(context, reason):
     assert context.response.reason == reason, f"Got {context.response.reason} instead"