Adding attribute schema class for attributes

This patch introduces simple schema class for attributes.
There are two options avaliable for this schema:
 - description
 - support status
It gives ability for adding support status for each attribute.

Change-Id: I46cbf776f315cbe6414005cbee65da1cefdc5f7d
Closes-Bug: #1305584

heat/engine/attributes.py

@@ -13,23 +13,72 @@
 
 import collections
 
+from heat.engine import constraints as constr
+from heat.engine import support
+
+
+class Schema(constr.Schema):
+    """
+    Simple schema class for attributes.
+
+    Schema objects are serialisable to dictionaries following a superset of
+    the HOT input Parameter schema using dict().
+    """
+
+    KEYS = (
+        DESCRIPTION,
+    ) = (
+        'description',
+    )
+
+    def __init__(self, description=None,
+                 support_status=support.SupportStatus()):
+        self.description = description
+        self.support_status = support_status
+
+    def __getitem__(self, key):
+        if key == self.DESCRIPTION:
+            if self.description is not None:
+                return self.description
+
+        raise KeyError(key)
+
+    @classmethod
+    def from_attribute(cls, schema_dict):
+        """
+        Return a Property Schema corresponding to a Attribute Schema.
+        """
+        if isinstance(schema_dict, cls):
+            return schema_dict
+        # it's necessary for supporting old attribute schema format,
+        # where value is not Schema object
+        return cls(description=schema_dict)
+
+
+def schemata(schema):
+    """
+    Return dictionary of Schema objects for given dictionary of schemata.
+    """
+    return dict((n, Schema.from_attribute(s)) for n, s in schema.items())
+
 
 class Attribute(object):
     """
     An Attribute schema.
     """
 
-    (DESCRIPTION,) = ('description',)
-
-    def __init__(self, attr_name, description):
+    def __init__(self, attr_name, schema):
         """
         Initialise with a name and description.
 
         :param attr_name: the name of the attribute
-        :param description: attribute description
+        :param schema: attribute schema
         """
         self.name = attr_name
-        self.description = description
+        self.schema = Schema.from_attribute(schema)
+
+    def support_status(self):
+        return self.schema.support_status
 
     def as_output(self, resource_name):
         """
@@ -42,7 +91,7 @@ class Attribute(object):
         return {
             "Value": '{"Fn::GetAtt": ["%s", "%s"]}' % (resource_name,
                                                        self.name),
-            "Description": self.description
+            "Description": self.schema.description
         }
 
 

heat/engine/service.py

@@ -787,9 +787,9 @@ class EngineService(service.Service):
                     yield name, dict(schema)
 
         def attributes_schema():
-            for schema_item in resource_class.attributes_schema.items():
-                schema = attributes.Attribute(*schema_item)
-                yield schema.name, {schema.DESCRIPTION: schema.description}
+            for name, schema_data in resource_class.attributes_schema.items():
+                schema = attributes.Schema.from_attribute(schema_data)
+                yield name, {schema.DESCRIPTION: schema.description}
 
         return {
             rpc_api.RES_SCHEMA_RES_TYPE: type_name,

heat/tests/test_attributes.py

@@ -11,10 +11,61 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import testtools
+
 from heat.engine import attributes
+from heat.engine import resources
+from heat.engine import support
 from heat.tests import common
 
 
+class AttributeSchemaTest(testtools.TestCase):
+    def test_schema_all(self):
+        d = {'description': 'A attribute'}
+        s = attributes.Schema('A attribute')
+        self.assertEqual(d, dict(s))
+
+    def test_all_resource_schemata(self):
+        for resource_type in resources.global_env().get_types():
+            for schema in getattr(resource_type,
+                                  'attributes_schema',
+                                  {}).itervalues():
+                attributes.Schema.from_attribute(schema)
+
+    def test_from_attribute_new_schema_format(self):
+        s = attributes.Schema('Test description.')
+        self.assertIs(s, attributes.Schema.from_attribute(s))
+        self.assertEqual('Test description.',
+                         attributes.Schema.from_attribute(s).description)
+
+    def test_schema_support_status(self):
+        schema = {
+            'foo_sup': attributes.Schema(
+                'Description1'
+            ),
+            'bar_dep': attributes.Schema(
+                'Description2',
+                support_status=support.SupportStatus(
+                    support.DEPRECATED,
+                    'Do not use this ever')
+            )
+        }
+        attrs = attributes.Attributes('test_rsrc', schema, lambda d: d)
+        self.assertEqual(support.SUPPORTED,
+                         attrs._attributes['foo_sup'].support_status().status)
+        self.assertEqual(support.DEPRECATED,
+                         attrs._attributes['bar_dep'].support_status().status)
+        self.assertEqual('Do not use this ever',
+                         attrs._attributes['bar_dep'].support_status().message)
+
+    def test_from_attribute_old_schema_format(self):
+        s = 'Test description.'
+        self.assertEqual(type(attributes.Schema(s)),
+                         type(attributes.Schema.from_attribute(s)))
+        self.assertEqual('Test description.',
+                         attributes.Schema.from_attribute(s).description)
+
+
 class AttributeTest(common.HeatTestCase):
     """Test the Attribute class."""