diff --git a/client/ociindex/ociindex_test.go b/client/ociindex/ociindex_test.go
new file mode 100644
index 000000000000..ff68dcf793f1
--- /dev/null
+++ b/client/ociindex/ociindex_test.go
@@ -0,0 +1,180 @@
+package ociindex
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/opencontainers/go-digest"
+	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEmptyDir(t *testing.T) {
+	dir := t.TempDir()
+	store := NewStoreIndex(dir)
+	idx, err := store.Read()
+	require.Error(t, err)
+	assert.Nil(t, idx)
+	assert.ErrorIs(t, err, os.ErrNotExist)
+}
+
+func TestReadIndex(t *testing.T) {
+	dir := t.TempDir()
+	idx := ocispecs.Index{
+		Manifests: []ocispecs.Descriptor{
+			randDescriptor("foo"),
+		},
+	}
+	dt, err := json.Marshal(idx)
+	require.NoError(t, err)
+	err = os.WriteFile(filepath.Join(dir, "index.json"), dt, 0644)
+	require.NoError(t, err)
+
+	store := NewStoreIndex(dir)
+	readIdx, err := store.Read()
+	require.NoError(t, err)
+	assert.Len(t, readIdx.Manifests, 1)
+
+	assert.Equal(t, idx.Manifests[0], readIdx.Manifests[0])
+}
+
+func TestReadByTag(t *testing.T) {
+	dir := t.TempDir()
+
+	one := randDescriptor("foo")
+	two := randDescriptor("bar")
+	three := randDescriptor("baz")
+
+	const refName = "org.opencontainers.image.ref.name"
+
+	two.Annotations = map[string]string{
+		refName: "ver1",
+	}
+	three.Annotations = map[string]string{
+		refName: "ver2",
+	}
+
+	idx := ocispecs.Index{
+		Manifests: []ocispecs.Descriptor{
+			one,
+			two,
+			three,
+		},
+	}
+	dt, err := json.Marshal(idx)
+	require.NoError(t, err)
+	err = os.WriteFile(filepath.Join(dir, "index.json"), dt, 0644)
+	require.NoError(t, err)
+
+	store := NewStoreIndex(dir)
+	desc, err := store.Get("ver1")
+	require.NoError(t, err)
+
+	assert.Equal(t, *desc, two)
+
+	desc, err = store.Get("ver3")
+	require.NoError(t, err)
+	assert.Nil(t, desc)
+}
+
+func TestWriteSingleDescriptor(t *testing.T) {
+	dir := t.TempDir()
+	store := NewStoreIndex(dir)
+
+	desc := randDescriptor("foo")
+	err := store.Put("", desc)
+	require.NoError(t, err)
+
+	readDesc, err := store.GetSingle()
+	require.NoError(t, err)
+	assert.Equal(t, desc, *readDesc)
+}
+
+func TestAddDescriptor(t *testing.T) {
+	dir := t.TempDir()
+
+	one := randDescriptor("foo")
+	two := randDescriptor("bar")
+
+	idx := ocispecs.Index{
+		Manifests: []ocispecs.Descriptor{
+			one,
+			two,
+		},
+	}
+	dt, err := json.Marshal(idx)
+	require.NoError(t, err)
+
+	err = os.WriteFile(filepath.Join(dir, "index.json"), dt, 0644)
+	require.NoError(t, err)
+
+	store := NewStoreIndex(dir)
+	three := randDescriptor("baz")
+	err = store.Put("", three)
+	require.NoError(t, err)
+
+	readIdx, err := store.Read()
+	require.NoError(t, err)
+
+	assert.Len(t, readIdx.Manifests, 3)
+	assert.Equal(t, one, readIdx.Manifests[0])
+	assert.Equal(t, two, readIdx.Manifests[1])
+	assert.Equal(t, three, readIdx.Manifests[2])
+
+	// store.Put also sets defaults for MediaType and SchemaVersion
+	assert.Equal(t, ocispecs.MediaTypeImageIndex, readIdx.MediaType)
+	assert.Equal(t, 2, readIdx.SchemaVersion)
+}
+
+func TestAddDescriptorWithTag(t *testing.T) {
+	dir := t.TempDir()
+
+	one := randDescriptor("foo")
+	two := randDescriptor("bar")
+
+	idx := ocispecs.Index{
+		Manifests: []ocispecs.Descriptor{
+			one,
+			two,
+		},
+	}
+	dt, err := json.Marshal(idx)
+	require.NoError(t, err)
+
+	err = os.WriteFile(filepath.Join(dir, "index.json"), dt, 0644)
+	require.NoError(t, err)
+
+	store := NewStoreIndex(dir)
+	three := randDescriptor("baz")
+	err = store.Put("ver1", three)
+	require.NoError(t, err)
+
+	desc, err := store.Get("ver1")
+	require.NoError(t, err)
+
+	assert.Equal(t, three.Digest, desc.Digest)
+	assert.Equal(t, three.Size, desc.Size)
+	assert.Equal(t, three.MediaType, desc.MediaType)
+
+	assert.Equal(t, "ver1", desc.Annotations["org.opencontainers.image.ref.name"])
+
+	readIdx, err := store.Read()
+	require.NoError(t, err)
+
+	assert.Len(t, readIdx.Manifests, 3)
+	assert.Equal(t, one, readIdx.Manifests[0])
+	assert.Equal(t, two, readIdx.Manifests[1])
+	assert.Equal(t, *desc, readIdx.Manifests[2])
+}
+
+func randDescriptor(seed string) ocispecs.Descriptor {
+	dgst := digest.FromBytes([]byte(seed))
+	return ocispecs.Descriptor{
+		MediaType: "application/vnd.test.descriptor+json",
+		Digest:    dgst,
+		Size:      int64(len(seed)),
+	}
+}