moby/layer/empty_test.go

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package layer
import (
"io"
"testing"
"github.com/docker/distribution/digest"
)
func TestEmptyLayer(t *testing.T) {
if EmptyLayer.ChainID() != ChainID(DigestSHA256EmptyTar) {
t.Fatal("wrong ID for empty layer")
}
if EmptyLayer.DiffID() != DigestSHA256EmptyTar {
t.Fatal("wrong DiffID for empty layer")
}
if EmptyLayer.Parent() != nil {
t.Fatal("expected no parent for empty layer")
}
if size, err := EmptyLayer.Size(); err != nil || size != 0 {
t.Fatal("expected zero size for empty layer")
}
if diffSize, err := EmptyLayer.DiffSize(); err != nil || diffSize != 0 {
t.Fatal("expected zero diffsize for empty layer")
}
tarStream, err := EmptyLayer.TarStream()
if err != nil {
t.Fatalf("error streaming tar for empty layer: %v", err)
}
digester := digest.Canonical.New()
_, err = io.Copy(digester.Hash(), tarStream)
if err != nil {
t.Fatalf("error hashing empty tar layer: %v", err)
}
if digester.Digest() != digest.Digest(DigestSHA256EmptyTar) {
t.Fatal("empty layer tar stream hashes to wrong value")
}
}