Use jsonschema draft-6

For now, this needs the pre-release version of jsonschema:
* python-jsonschema/jsonschema#337
* https://pypi.org/project/jsonschema/#history

README.rst

@@ -96,6 +96,7 @@ tool.)
 
     virtualenv -p python3 env
     source env/bin/activate
+    pip install --upgrade --pre jsonschema
     pip install -r requirements.txt
     pip install -e .
 

buildspec.yml

@@ -3,6 +3,7 @@ phases:
   pre_build:
     commands:
       - pip install --upgrade pip wheel -r requirements.txt .
+      - pip install --upgrade --pre jsonschema
   build:
     commands:
       - isort --check-only --verbose --recursive "setup.py" "run_lint" "uluru/" "tests/"

uluru/data_loaders.py

@@ -1,9 +1,10 @@
 import json
 import logging
 
-import jsonschema
 import pkg_resources
 import yaml
+from jsonschema import Draft6Validator
+from jsonschema.exceptions import ValidationError
 
 LOG = logging.getLogger(__name__)
 
@@ -22,10 +23,10 @@ def load_resource_spec(resource_spec_file):
     ) as f:
         resource_spec_schema = json.load(f)
 
+    validator = Draft6Validator(resource_spec_schema)
     try:
-        jsonschema.validate(resource_spec, resource_spec_schema)
-        # the unit tests should catch `SchemaError`/if the schema is invalid
-    except jsonschema.exceptions.ValidationError as e:
+        validator.validate(resource_spec)
+    except ValidationError as e:
         LOG.error(
             "The resource provider definition is invalid: %s", e.message  # noqa: B306
         )
@@ -57,10 +58,10 @@ def load_project_settings(plugin, project_settings_file):
             "to further customize code generation."
         )
 
+    validator = Draft6Validator(plugin.project_settings_schema())
     try:
-        jsonschema.validate(project_settings, plugin.project_settings_schema())
-        # the unit tests should catch `SchemaError`/if the schema is invalid
-    except jsonschema.exceptions.ValidationError as e:
+        validator.validate(project_settings)
+    except ValidationError as e:
         LOG.error("The project settings are invalid: %s", e.message)  # noqa: B306
         raise  # TODO: error handling