Update manifest code with new type

copy/manifest.go

@@ -79,10 +79,10 @@ func (ic *imageCopier) determineManifestConversion(ctx context.Context, destSupp
 	if _, ok := supportedByDest[srcType]; ok {
 		prioritizedTypes.append(srcType)
 	}
-	if !ic.canModifyManifest {
-		// We could also drop the !ic.canModifyManifest check and have the caller
+	if ic.canModifyManifest != "" {
+		// We could also drop this check and have the caller
 		// make the choice; it is already doing that to an extent, to improve error
-		// messages.  But it is nice to hide the “if !ic.canModifyManifest, do no conversion”
+		// messages.  But it is nice to hide the “if we can't modify, do no conversion”
 		// special case in here; the caller can then worry (or not) only about a good UI.
 		logrus.Debugf("We can't modify the manifest, hoping for the best...")
 		return srcType, []string{}, nil // Take our chances - FIXME? Or should we fail without trying?

copy/manifest_test.go

@@ -145,7 +145,7 @@ func TestDetermineManifestConversion(t *testing.T) {
 		ic := &imageCopier{
 			manifestUpdates:   &types.ManifestUpdateOptions{},
 			src:               src,
-			canModifyManifest: true,
+			canModifyManifest: "",
 		}
 		preferredMIMEType, otherCandidates, err := ic.determineManifestConversion(context.Background(), c.destTypes, "", false)
 		require.NoError(t, err, c.description)
@@ -164,7 +164,7 @@ func TestDetermineManifestConversion(t *testing.T) {
 		ic := &imageCopier{
 			manifestUpdates:   &types.ManifestUpdateOptions{},
 			src:               src,
-			canModifyManifest: false,
+			canModifyManifest: "Preserving digests",
 		}
 		preferredMIMEType, otherCandidates, err := ic.determineManifestConversion(context.Background(), c.destTypes, "", false)
 		require.NoError(t, err, c.description)
@@ -179,7 +179,7 @@ func TestDetermineManifestConversion(t *testing.T) {
 		ic := &imageCopier{
 			manifestUpdates:   &types.ManifestUpdateOptions{},
 			src:               src,
-			canModifyManifest: true,
+			canModifyManifest: "",
 		}
 		preferredMIMEType, otherCandidates, err := ic.determineManifestConversion(context.Background(), c.destTypes, v1.MediaTypeImageManifest, false)
 		require.NoError(t, err, c.description)
@@ -192,7 +192,7 @@ func TestDetermineManifestConversion(t *testing.T) {
 	ic := imageCopier{
 		manifestUpdates:   &types.ManifestUpdateOptions{},
 		src:               fakeImageSource(""),
-		canModifyManifest: true,
+		canModifyManifest: "",
 	}
 	_, _, err := ic.determineManifestConversion(context.Background(), supportS1S2, "", false)
 	assert.Error(t, err)