oci package passing tests

Signed-off-by: Daniel Nephin <dnephin@gmail.com>

oci/client.go

@@ -0,0 +1,21 @@
+package oci
+
+import (
+	"context"
+
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/snapshot"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// Client interface used by SpecOpt
+type Client interface {
+	SnapshotService(snapshotterName string) snapshot.Snapshotter
+	ContentStore() content.Store
+}
+
+// Image interface used by some SpecOpt to query image configuration
+type Image interface {
+	// Config descriptor for the image.
+	Config(ctx context.Context) (ocispec.Descriptor, error)
+}