Adjustments based on code review feedback

image/docker/interfaces.py

@@ -4,9 +4,13 @@ from six import add_metaclass
 @add_metaclass(ABCMeta)
 class ManifestInterface(object):
   """ Defines the interface for the various manifests types supported. """
+  @abstractproperty
+  def is_manifest_list(self):
+    """ Returns whether this manifest is a list. """
+
   @abstractproperty
   def schema_version(self):
-    """ The version of the schema, or None for lists. """
+    """ The version of the schema. """
 
   @abstractproperty
   def digest(self):

image/docker/schema1.py

@@ -206,6 +206,10 @@ class DockerSchema1Manifest(ManifestInterface):
       if not verified:
         raise InvalidSchema1Signature()
 
+  @property
+  def is_manifest_list(self):
+    return False
+
   @property
   def schema_version(self):
     return 1

image/docker/schema2/list.py

@@ -183,10 +183,14 @@ class DockerSchema2ManifestList(ManifestInterface):
     except ValidationError as ve:
       raise MalformedSchema2ManifestList('manifest data does not match schema: %s' % ve)
 
+  @property
+  def is_manifest_list(self):
+    """ Returns whether this manifest is a list. """
+    return True
+
   @property
   def schema_version(self):
-    """ The version of the schema, or None for lists. """
-    return None
+    return 2
 
   @property
   def digest(self):

image/docker/schema2/manifest.py

@@ -140,6 +140,10 @@ class DockerSchema2Manifest(ManifestInterface):
       if layer.is_remote and not layer.urls:
         raise MalformedSchema2Manifest('missing `urls` for remote layer')
 
+  @property
+  def is_manifest_list(self):
+    return False
+
   @property
   def schema_version(self):
     return 2

image/docker/schema2/test/test_list.py

@@ -75,8 +75,6 @@ def test_valid_manifestlist():
 
   manifestlist = DockerSchema2ManifestList(MANIFESTLIST_BYTES)
   assert len(manifestlist.manifests(_get_manifest)) == 2
-  assert (manifestlist.digest ==
-          'sha256:340d7dadea77035533a2d43e8ff711ecca1965978a6e7699b87e32b35f76038d')
 
   assert manifestlist.media_type == 'application/vnd.docker.distribution.manifest.list.v2+json'
   assert manifestlist.bytes == MANIFESTLIST_BYTES
@@ -108,8 +106,6 @@ def test_get_v1_compatible_manifest_no_matching_list():
 
   manifestlist = DockerSchema2ManifestList(NO_AMD_MANIFESTLIST_BYTES)
   assert len(manifestlist.manifests(_get_manifest)) == 1
-  assert (manifestlist.digest ==
-          'sha256:40ed1cfe692333bfa519a9bfed9676975a990fff5afd35efa628320c39c793ca')
 
   assert manifestlist.media_type == 'application/vnd.docker.distribution.manifest.list.v2+json'
   assert manifestlist.bytes == NO_AMD_MANIFESTLIST_BYTES