Enhancements for Docker schema implementations in preparing for supporting schema 2 in the OCI model

This adds additional required properties and methods to the Docker schema interface to allow us to treat both schema1 and schema2 manifests and lists logically equivalent from the OCI mode perspective

image/docker/schema2/test/test_list.py

@@ -3,7 +3,8 @@ import pytest
 
 from image.docker.schema1 import DockerSchema1Manifest
 from image.docker.schema2.manifest import DockerSchema2Manifest
-from image.docker.schema2.list import MalformedSchema2ManifestList, DockerSchema2ManifestList
+from image.docker.schema2.list import (MalformedSchema2ManifestList, DockerSchema2ManifestList,
+                                       DockerSchema2ManifestListBuilder)
 from image.docker.schema2.test.test_manifest import MANIFEST_BYTES as v22_bytes
 from image.docker.test.test_schema1 import MANIFEST_BYTES as v21_bytes
 
@@ -58,6 +59,13 @@ def test_valid_manifestlist():
 
   manifestlist = DockerSchema2ManifestList(MANIFESTLIST_BYTES)
   assert len(manifestlist.manifests(_get_manifest)) == 2
+  assert (manifestlist.digest ==
+          'sha256:7e22fdbe49736329786c9b4fdc154cc9251b190ca6b4cf33aed00efc0fc3df25')
+
+  assert manifestlist.media_type == 'application/vnd.docker.distribution.manifest.list.v2+json'
+  assert manifestlist.bytes == MANIFESTLIST_BYTES
+  assert manifestlist.manifest_dict == json.loads(MANIFESTLIST_BYTES)
+  assert set(manifestlist.blob_digests) == {'sha256:e6', 'sha256:5b'}
 
   for index, manifest in enumerate(manifestlist.manifests(_get_manifest)):
     if index == 0:
@@ -68,3 +76,25 @@ def test_valid_manifestlist():
       assert manifest.manifest_obj.schema_version == 1
 
   assert manifestlist.get_v1_compatible_manifest(_get_manifest).manifest_obj.schema_version == 1
+
+  assert manifestlist.layers is None
+  assert manifestlist.leaf_layer_v1_image_id is None
+  assert manifestlist.legacy_image_ids is None
+
+
+def test_builder():
+  def _get_manifest(digest):
+    if digest == 'sha256:e6':
+      return v22_bytes
+    else:
+      return v21_bytes
+
+  existing = DockerSchema2ManifestList(MANIFESTLIST_BYTES)
+
+  builder = DockerSchema2ManifestListBuilder()
+  for index, manifest in enumerate(existing.manifests(_get_manifest)):
+    builder.add_manifest(manifest.manifest_obj, "amd64", "os")
+
+  built = builder.build()
+  assert len(built.manifests(_get_manifest)) == 2
+