Try to fix restorer acceptance

Signed-off-by: Natalie Arellano <[email protected]>

acceptance/restorer_test.go

@@ -131,14 +131,15 @@ func testRestorerFunc(platformAPI string) func(t *testing.T, when spec.G, it spe
 		when("using cache-dir", func() {
 			when("there is cache present from a previous build", func() {
 				it("restores cached layer data", func() {
-					h.DockerRunAndCopy(t,
+					output := h.DockerRunAndCopy(t,
 						containerName,
 						copyDir,
 						"/layers",
 						restoreImage,
 						h.WithFlags("--env", "CNB_PLATFORM_API="+platformAPI),
 						h.WithArgs("-cache-dir", "/cache"),
 					)
+					t.Log("XXX", output)
 
 					// check restored cache file is present
 					cachedFile := filepath.Join(copyDir, "layers", "cacher_buildpack", "cached-layer", "data")

cache/volume_cache.go

@@ -2,7 +2,6 @@ package cache
 
 import (
 	"crypto/sha256"
-	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -241,7 +240,7 @@ func (c *VolumeCache) VerifyLayer(diffID string) error {
 	if _, err := io.Copy(hasher, layerRC); err != nil {
 		return errors.Wrap(err, "hashing layer")
 	}
-	foundDiffID := "sha256:" + hex.EncodeToString(hasher.Sum(make([]byte, 0, hasher.Size())))
+	foundDiffID := fmt.Sprintf("sha256:%x", hasher.Sum(nil))
 	if diffID != foundDiffID {
 		return NewReadErr(fmt.Sprintf("expected layer contents to have SHA '%s'; found '%s'", diffID, foundDiffID))
 	}