1 files changed, 183 insertions, 0 deletions
diff --git a/pkg/v1/remote/referrers_test.go b/pkg/v1/remote/referrers_test.go
new file mode 100644
index 0000000..91f9edc
--- /dev/null
+++ b/pkg/v1/remote/referrers_test.go
@@ -0,0 +1,183 @@
+// Copyright 2023 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package remote_test
+
+import (
+	"fmt"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/registry"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/random"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+func TestReferrers(t *testing.T) {
+	// Run all tests against:
+	//
+	//   (1) A OCI 1.0 registry (without referrers API)
+	//   (2) An OCI 1.1+ registry (with referrers API)
+	//
+	for _, leg := range []struct {
+		server      *httptest.Server
+		tryFallback bool
+	}{
+		{
+			server:      httptest.NewServer(registry.New(registry.WithReferrersSupport(false))),
+			tryFallback: true,
+		},
+		{
+			server:      httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			tryFallback: false,
+		},
+	} {
+		s := leg.server
+		defer s.Close()
+		u, err := url.Parse(s.URL)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		descriptor := func(img v1.Image) v1.Descriptor {
+			d, err := img.Digest()
+			if err != nil {
+				t.Fatal(err)
+			}
+			sz, err := img.Size()
+			if err != nil {
+				t.Fatal(err)
+			}
+			mt, err := img.MediaType()
+			if err != nil {
+				t.Fatal(err)
+			}
+			return v1.Descriptor{
+				Digest:       d,
+				Size:         sz,
+				MediaType:    mt,
+				ArtifactType: "application/testing123",
+			}
+		}
+
+		// Push an image we'll attach things to.
+		// We'll copy from src to dst.
+		rootRef, err := name.ParseReference(fmt.Sprintf("%s/repo:root", u.Host))
+		if err != nil {
+			t.Fatal(err)
+		}
+		rootImg, err := random.Image(10, 10)
+		if err != nil {
+			t.Fatal(err)
+		}
+		rootImg = mutate.ConfigMediaType(rootImg, types.MediaType("application/testing123"))
+		if err := remote.Write(rootRef, rootImg); err != nil {
+			t.Fatal(err)
+		}
+		rootDesc := descriptor(rootImg)
+		t.Logf("root image is %s", rootDesc.Digest)
+
+		// Push an image that refers to the root image as its subject.
+		leafRef, err := name.ParseReference(fmt.Sprintf("%s/repo:leaf", u.Host))
+		if err != nil {
+			t.Fatal(err)
+		}
+		leafImg, err := random.Image(20, 20)
+		if err != nil {
+			t.Fatal(err)
+		}
+		leafImg = mutate.ConfigMediaType(leafImg, types.MediaType("application/testing123"))
+		leafImg = mutate.Subject(leafImg, rootDesc).(v1.Image)
+		if err := remote.Write(leafRef, leafImg); err != nil {
+			t.Fatal(err)
+		}
+		leafDesc := descriptor(leafImg)
+		t.Logf("leaf image is %s", leafDesc.Digest)
+
+		// Get the referrers of the root image, by digest.
+		rootRefDigest := rootRef.Context().Digest(rootDesc.Digest.String())
+		index, err := remote.Referrers(rootRefDigest)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if d := cmp.Diff([]v1.Descriptor{leafDesc}, index.Manifests); d != "" {
+			t.Fatalf("referrers diff (-want,+got): %s", d)
+		}
+
+		if leg.tryFallback {
+			// Get the referrers by querying the root image's fallback tag directly.
+			tag, err := name.ParseReference(fmt.Sprintf("%s/repo:sha256-%s", u.Host, rootDesc.Digest.Hex))
+			if err != nil {
+				t.Fatal(err)
+			}
+			idx, err := remote.Index(tag)
+			if err != nil {
+				t.Fatal(err)
+			}
+			mf, err := idx.IndexManifest()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if d := cmp.Diff(index.Manifests, mf.Manifests); d != "" {
+				t.Fatalf("fallback tag diff (-want,+got): %s", d)
+			}
+		}
+
+		// Push the leaf image again, this time with a different tag.
+		// This shouldn't add another item to the root image's referrers,
+		// because it's the same digest.
+		// Push an image that refers to the root image as its subject.
+		leaf2Ref, err := name.ParseReference(fmt.Sprintf("%s/repo:leaf2", u.Host))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := remote.Write(leaf2Ref, leafImg); err != nil {
+			t.Fatal(err)
+		}
+		// Get the referrers of the root image again, which should only have one entry.
+		rootRefDigest = rootRef.Context().Digest(rootDesc.Digest.String())
+		index, err = remote.Referrers(rootRefDigest)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if d := cmp.Diff([]v1.Descriptor{leafDesc}, index.Manifests); d != "" {
+			t.Fatalf("referrers diff after second push (-want,+got): %s", d)
+		}
+
+		// Try applying filters and verify number of manifests and and annotations
+		index, err = remote.Referrers(rootRefDigest,
+			remote.WithFilter("artifactType", "application/testing123"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if numManifests := len(index.Manifests); numManifests == 0 {
+			t.Fatal("index contained 0 manifests")
+		}
+
+		index, err = remote.Referrers(rootRefDigest,
+			remote.WithFilter("artifactType", "application/testing123BADDDD"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if numManifests := len(index.Manifests); numManifests != 0 {
+			t.Fatalf("expected index to contain 0 manifests, but had %d", numManifests)
+		}
+	}
+}