validate server action 'console_output' attributes

This patch adds the JSON schema for Nova V2 & V3 get_console_output
server action APIs response and validate the response with added
JSON schema to block the backward incompatibility change in the future.

The response body of get_console_output V2 & V3 APIs is same and given
below:

{
        "output": "FAKE CONSOLE OUTPUT\nANOTHER\nLAST LINE"
}

Partially implements blueprint nova-api-attribute-test

Change-Id: I22e61d1fed926aa9a310a46b12748db401dec045
diff --git a/tempest/api_schema/compute/servers.py b/tempest/api_schema/compute/servers.py
index fb39087..2002927 100644
--- a/tempest/api_schema/compute/servers.py
+++ b/tempest/api_schema/compute/servers.py
@@ -147,3 +147,14 @@
 server_actions_delete_password = {
     'status_code': [204]
 }
+
+get_console_output = {
+    'status_code': [200],
+    'response_body': {
+        'type': 'object',
+        'properties': {
+            'output': {'type': 'string'}
+        },
+        'required': ['output']
+    }
+}
diff --git a/tempest/services/compute/json/servers_client.py b/tempest/services/compute/json/servers_client.py
index 9c7eec6..77c73df 100644
--- a/tempest/services/compute/json/servers_client.py
+++ b/tempest/services/compute/json/servers_client.py
@@ -210,11 +210,13 @@
                                post_body)
         if response_key is not None:
             body = json.loads(body)
-            # Check for Schema as 'None' because if we donot have any server
+            # Check for Schema as 'None' because if we do not have any server
             # action schema implemented yet then they can pass 'None' to skip
             # the validation.Once all server action has their schema
             # implemented then, this check can be removed if every actions are
             # supposed to validate their response.
+            # TODO(GMann): Remove the below 'if' check once all server actions
+            # schema are implemented.
             if schema is not None:
                 self.validate_response(schema, resp, body)
             body = body[response_key]
@@ -427,7 +429,7 @@
 
     def get_console_output(self, server_id, length):
         return self.action(server_id, 'os-getConsoleOutput', 'output',
-                           None, length=length)
+                           common_schema.get_console_output, length=length)
 
     def list_virtual_interfaces(self, server_id):
         """
diff --git a/tempest/services/compute/v3/json/servers_client.py b/tempest/services/compute/v3/json/servers_client.py
index caa0a1d..2a83f88 100644
--- a/tempest/services/compute/v3/json/servers_client.py
+++ b/tempest/services/compute/v3/json/servers_client.py
@@ -209,7 +209,17 @@
         resp, body = self.post('servers/%s/action' % str(server_id),
                                post_body)
         if response_key is not None:
-            body = json.loads(body)[response_key]
+            body = json.loads(body)
+            # Check for Schema as 'None' because if we do not have any server
+            # action schema implemented yet then they can pass 'None' to skip
+            # the validation.Once all server action has their schema
+            # implemented then, this check can be removed if every actions are
+            # supposed to validate their response.
+            # TODO(GMann): Remove the below 'if' check once all server actions
+            # schema are implemented.
+            if schema is not None:
+                self.validate_response(schema, resp, body)
+            body = body[response_key]
         else:
             self.validate_response(schema, resp, body)
         return resp, body
@@ -256,7 +266,7 @@
         if 'disk_config' in kwargs:
             kwargs['os-disk-config:disk_config'] = kwargs['disk_config']
             del kwargs['disk_config']
-        return self.action(server_id, 'rebuild', 'server', **kwargs)
+        return self.action(server_id, 'rebuild', 'server', None, **kwargs)
 
     def resize(self, server_id, flavor_ref, **kwargs):
         """Changes the flavor of a server."""
@@ -421,11 +431,12 @@
 
     def get_console_output(self, server_id, length):
         return self.action(server_id, 'get_console_output', 'output',
-                           length=length)
+                           common_schema.get_console_output, length=length)
 
     def rescue_server(self, server_id, **kwargs):
         """Rescue the provided server."""
-        return self.action(server_id, 'rescue', 'admin_password', **kwargs)
+        return self.action(server_id, 'rescue', 'admin_password',
+                           None, **kwargs)
 
     def unrescue_server(self, server_id):
         """Unrescue the provided server."""
@@ -483,9 +494,9 @@
     def get_spice_console(self, server_id, console_type):
         """Get URL of Spice console."""
         return self.action(server_id, "get_spice_console"
-                           "console", type=console_type)
+                           "console", None, type=console_type)
 
     def get_rdp_console(self, server_id, console_type):
         """Get URL of RDP console."""
         return self.action(server_id, "get_rdp_console"
-                           "console", type=console_type)
+                           "console", None, type=console_type)