Explicitly add json schema validator for schema validation

JSON Schema use validator (draft3 or draft4) to validate the
given schema against given instance.
By default it use draft4 validator which is current one. If new validator
will be released in future and that become default then, there might be some
compatibility issues between draft4 and new version.

For example from draft3 to draft4, 'ip-version' format has been changed to 'ipv4'.

This commits explicitly pass the validator while doing the schema validation.
Also adds unit tests to check the current version of validator.

If any new validator will be available in future, then we can use that by doing
proper modification in schema files if needed.

Change-Id: Ie11e3ba60926f247a82670b7da37d7890d16280c

tempest_lib/common/rest_client.py

@@ -34,7 +34,8 @@ MAX_RECURSION_DEPTH = 2
 # All the successful HTTP status codes from RFC 7231 & 4918
 HTTP_SUCCESS = (200, 201, 202, 203, 204, 205, 206, 207)
 
-# JSON Schema format checker used for JSON Schema validation
+# JSON Schema validator and format checker used for JSON Schema validation
+JSONSCHEMA_VALIDATOR = jsonschema.Draft4Validator
 FORMAT_CHECKER = jsonschema.draft4_format_checker
 
 
@@ -809,6 +810,7 @@ class RestClient(object):
             if body_schema:
                 try:
                     jsonschema.validate(body, body_schema,
+                                        cls=JSONSCHEMA_VALIDATOR,
                                         format_checker=FORMAT_CHECKER)
                 except jsonschema.ValidationError as ex:
                     msg = ("HTTP response body is invalid (%s)") % ex
@@ -823,6 +825,7 @@ class RestClient(object):
             if header_schema:
                 try:
                     jsonschema.validate(resp, header_schema,
+                                        cls=JSONSCHEMA_VALIDATOR,
                                         format_checker=FORMAT_CHECKER)
                 except jsonschema.ValidationError as ex:
                     msg = ("HTTP response header is invalid (%s)") % ex

tempest_lib/tests/test_rest_client.py

@@ -15,6 +15,7 @@
 import json
 
 import httplib2
+import jsonschema
 from oslotest import mockpatch
 import six
 
@@ -1027,3 +1028,24 @@ class TestRestClientJSONSchemaFormatValidation(TestJSONSchemaValidationBase):
         }
         body = {'foo': 'example@example.com'}
         self._test_validate_pass(schema, body)
+
+
+class TestRestClientJSONSchemaValidatorVersion(TestJSONSchemaValidationBase):
+
+    schema = {
+        'status_code': [200],
+        'response_body': {
+            'type': 'object',
+            'properties': {
+                'foo': {'type': 'string'}
+            }
+        }
+    }
+
+    def test_current_json_schema_validator_version(self):
+        with mockpatch.PatchObject(jsonschema.Draft4Validator,
+                                   "check_schema") as chk_schema:
+            body = {'foo': 'test'}
+            self._test_validate_pass(self.schema, body)
+            chk_schema.mock.assert_called_once_with(
+                self.schema['response_body'])