test: use T.TempDir to create temporary test directory

The directory created by `T.TempDir` is automatically removed when the
test and all its subtests complete.

Reference: https://pkg.go.dev/testing#T.TempDir
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

pkg/storage/storage_test.go

@@ -6,7 +6,6 @@ import (
 	_ "crypto/sha256"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path"
 	"strings"
@@ -111,12 +110,7 @@ func TestStorageAPIs(t *testing.T) {
 				store, imgStore, _ = createObjectsStore(testDir)
 				defer cleanupStorage(store, testDir)
 			} else {
-				dir, err := ioutil.TempDir("", "oci-repo-test")
-				if err != nil {
-					panic(err)
-				}
-
-				defer os.RemoveAll(dir)
+				dir := t.TempDir()
 
 				log := log.Logger{Logger: zerolog.New(os.Stdout)}
 				metrics := monitoring.NewMetricsServer(false, log)
@@ -686,25 +680,9 @@ func TestStorageHandler(t *testing.T) {
 				defer cleanupStorage(thirdStorageDriver, thirdRootDir)
 			} else {
 				// Create temporary directory
-				var err error
-
-				firstRootDir, err = ioutil.TempDir("", "util_test")
-				if err != nil {
-					panic(err)
-				}
-				defer os.RemoveAll(firstRootDir)
-
-				secondRootDir, err = ioutil.TempDir("", "util_test")
-				if err != nil {
-					panic(err)
-				}
-				defer os.RemoveAll(secondRootDir)
-
-				thirdRootDir, err = ioutil.TempDir("", "util_test")
-				if err != nil {
-					panic(err)
-				}
-				defer os.RemoveAll(thirdRootDir)
+				firstRootDir = t.TempDir()
+				secondRootDir = t.TempDir()
+				thirdRootDir = t.TempDir()
 
 				log := log.NewLogger("debug", "")