Add support for manifest list ("fat manifest")

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

manifest/manifestlist/manifestlist_test.go

@@ -0,0 +1,111 @@
+package manifestlist
+
+import (
+	"bytes"
+	"encoding/json"
+	"reflect"
+	"testing"
+
+	"github.com/docker/distribution"
+)
+
+var expectedManifestListSerialization = []byte(`{
+   "schemaVersion": 2,
+   "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
+   "manifests": [
+      {
+         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
+         "size": 985,
+         "digest": "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
+         "platform": {
+            "architecture": "amd64",
+            "os": "linux",
+            "features": [
+               "sse4"
+            ]
+         }
+      },
+      {
+         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
+         "size": 2392,
+         "digest": "sha256:6346340964309634683409684360934680934608934608934608934068934608",
+         "platform": {
+            "architecture": "sun4m",
+            "os": "sunos"
+         }
+      }
+   ]
+}`)
+
+func TestManifestList(t *testing.T) {
+	manifestDescriptors := []ManifestDescriptor{
+		{
+			Descriptor: distribution.Descriptor{
+				Digest:    "sha256:1a9ec845ee94c202b2d5da74a24f0ed2058318bfa9879fa541efaecba272e86b",
+				Size:      985,
+				MediaType: "application/vnd.docker.distribution.manifest.v2+json",
+			},
+			Platform: PlatformSpec{
+				Architecture: "amd64",
+				OS:           "linux",
+				Features:     []string{"sse4"},
+			},
+		},
+		{
+			Descriptor: distribution.Descriptor{
+				Digest:    "sha256:6346340964309634683409684360934680934608934608934608934068934608",
+				Size:      2392,
+				MediaType: "application/vnd.docker.distribution.manifest.v2+json",
+			},
+			Platform: PlatformSpec{
+				Architecture: "sun4m",
+				OS:           "sunos",
+			},
+		},
+	}
+
+	deserialized, err := FromDescriptors(manifestDescriptors)
+	if err != nil {
+		t.Fatalf("error creating DeserializedManifestList: %v", err)
+	}
+
+	mediaType, canonical, err := deserialized.Payload()
+
+	if mediaType != MediaTypeManifestList {
+		t.Fatalf("unexpected media type: %s", mediaType)
+	}
+
+	// Check that the canonical field is the same as json.MarshalIndent
+	// with these parameters.
+	p, err := json.MarshalIndent(&deserialized.ManifestList, "", "   ")
+	if err != nil {
+		t.Fatalf("error marshaling manifest list: %v", err)
+	}
+	if !bytes.Equal(p, canonical) {
+		t.Fatalf("manifest bytes not equal: %q != %q", string(canonical), string(p))
+	}
+
+	// Check that the canonical field has the expected value.
+	if !bytes.Equal(expectedManifestListSerialization, canonical) {
+		t.Fatalf("manifest bytes not equal: %q != %q", string(canonical), string(expectedManifestListSerialization))
+	}
+
+	var unmarshalled DeserializedManifestList
+	if err := json.Unmarshal(deserialized.canonical, &unmarshalled); err != nil {
+		t.Fatalf("error unmarshaling manifest: %v", err)
+	}
+
+	if !reflect.DeepEqual(&unmarshalled, deserialized) {
+		t.Fatalf("manifests are different after unmarshaling: %v != %v", unmarshalled, *deserialized)
+	}
+
+	references := deserialized.References()
+	if len(references) != 2 {
+		t.Fatalf("unexpected number of references: %d", len(references))
+	}
+	for i := range references {
+		if !reflect.DeepEqual(references[i], manifestDescriptors[i].Descriptor) {
+			t.Fatalf("unexpected value %d returned by References: %v", i, references[i])
+		}
+	}
+}