1 files changed, 154 insertions, 0 deletions
diff --git a/pkg/v1/cache/cache_test.go b/pkg/v1/cache/cache_test.go
new file mode 100644
index 0000000..ee5091b
--- /dev/null
+++ b/pkg/v1/cache/cache_test.go
@@ -0,0 +1,154 @@
+// Copyright 2021 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 cache
+
+import (
+	"errors"
+	"io"
+	"testing"
+
+	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/validate"
+)
+
+func TestImage(t *testing.T) {
+	img, err := random.Image(1024, 5)
+	if err != nil {
+		t.Fatalf("random.Image: %v", err)
+	}
+	m := &memcache{map[v1.Hash]v1.Layer{}}
+	img = Image(img, m)
+
+	// Validate twice to hit the cache.
+	if err := validate.Image(img); err != nil {
+		t.Errorf("Validate: %v", err)
+	}
+	if err := validate.Image(img); err != nil {
+		t.Errorf("Validate: %v", err)
+	}
+}
+
+func TestImageIndex(t *testing.T) {
+	// ImageIndex with child Image and ImageIndex manifests.
+	ii, err := random.Index(1024, 5, 2)
+	if err != nil {
+		t.Fatalf("random.Index: %v", err)
+	}
+	iiChild, err := random.Index(1024, 5, 2)
+	if err != nil {
+		t.Fatalf("random.Index: %v", err)
+	}
+	ii = mutate.AppendManifests(ii, mutate.IndexAddendum{Add: iiChild})
+
+	m := &memcache{map[v1.Hash]v1.Layer{}}
+	ii = ImageIndex(ii, m)
+
+	// Validate twice to hit the cache.
+	if err := validate.Index(ii); err != nil {
+		t.Errorf("Validate: %v", err)
+	}
+	if err := validate.Index(ii); err != nil {
+		t.Errorf("Validate: %v", err)
+	}
+}
+
+func TestLayersLazy(t *testing.T) {
+	img, err := random.Image(1024, 5)
+	if err != nil {
+		t.Fatalf("random.Image: %v", err)
+	}
+	m := &memcache{map[v1.Hash]v1.Layer{}}
+	img = Image(img, m)
+
+	layers, err := img.Layers()
+	if err != nil {
+		t.Fatalf("img.Layers: %v", err)
+	}
+
+	// After calling Layers, nothing is cached.
+	if got, want := len(m.m), 0; got != want {
+		t.Errorf("Cache has %d entries, want %d", got, want)
+	}
+
+	rc, err := layers[0].Uncompressed()
+	if err != nil {
+		t.Fatalf("layer.Uncompressed: %v", err)
+	}
+	io.Copy(io.Discard, rc)
+
+	if got, expected := len(m.m), 1; got != expected {
+		t.Errorf("expected %v layers in cache after reading, got %v", expected, got)
+	}
+}
+
+// TestCacheShortCircuit tests that if a layer is found in the cache,
+// LayerByDigest is not called in the underlying Image implementation.
+func TestCacheShortCircuit(t *testing.T) {
+	l := &fakeLayer{}
+	m := &memcache{map[v1.Hash]v1.Layer{
+		fakeHash: l,
+	}}
+	img := Image(&fakeImage{}, m)
+
+	for i := 0; i < 10; i++ {
+		if _, err := img.LayerByDigest(fakeHash); err != nil {
+			t.Errorf("LayerByDigest[%d]: %v", i, err)
+		}
+	}
+}
+
+var fakeHash = v1.Hash{Algorithm: "fake", Hex: "data"}
+
+type fakeLayer struct{ v1.Layer }
+type fakeImage struct{ v1.Image }
+
+func (f *fakeImage) LayerByDigest(v1.Hash) (v1.Layer, error) {
+	return nil, errors.New("LayerByDigest was called")
+}
+
+// memcache is an in-memory Cache implementation.
+//
+// It doesn't intend to actually write layer data, it just keeps a reference
+// to the original Layer.
+//
+// It only assumes/considers compressed layers, and so only writes layers by
+// digest.
+type memcache struct {
+	m map[v1.Hash]v1.Layer
+}
+
+func (m *memcache) Put(l v1.Layer) (v1.Layer, error) {
+	digest, err := l.Digest()
+	if err != nil {
+		return nil, err
+	}
+	m.m[digest] = l
+	return l, nil
+}
+
+func (m *memcache) Get(h v1.Hash) (v1.Layer, error) {
+	l, found := m.m[h]
+	if !found {
+		return nil, ErrNotFound
+	}
+	return l, nil
+}
+
+func (m *memcache) Delete(h v1.Hash) error {
+	delete(m.m, h)
+	return nil
+}