Add blob mounting tests to the new registry test suite

test/registry/protocols.py

@@ -51,6 +51,7 @@ class Failures(Enum):
   UNSUPPORTED_CONTENT_TYPE = 'unsupported-content-type'
   INVALID_BLOB = 'invalid-blob'
   NAMESPACE_DISABLED = 'namespace-disabled'
+  UNAUTHORIZED_FOR_MOUNT = 'unauthorized-for-mount'
 
 
 class ProtocolOptions(object):
@@ -62,6 +63,7 @@ class ProtocolOptions(object):
     self.chunks_for_upload = None
     self.skip_head_checks = False
     self.manifest_content_type = None
+    self.mount_blobs = None
 
 
 @add_metaclass(ABCMeta)