Increase Unit Test Code Coverage

Unit test coverge was increased to cover the usages of crypto. This helps to ensure that everything is working fine with fips mode enabled.
Also updated sha1 to sha256 in registry/storage/driver/testsuites/testsuites.go because sha1 is not supported in fips mode.

Signed-off-by: Naveed Jamil <naveed.jamil@tenpearl.com>

contrib/token-server/token_test.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"encoding/base64"
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/docker/distribution/registry/auth"
+	"github.com/docker/libtrust"
+	"strings"
+)
+
+func TestCreateJWTSuccessWithEmptyACL(t *testing.T) {
+	key, err := rsa.GenerateKey(rand.Reader, 1024)
+	if err != nil {
+		t.Fatal(err)
+	}
+	pk, err := libtrust.FromCryptoPrivateKey(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tokenIssuer := TokenIssuer{
+		Expiration: time.Duration(100),
+		Issuer:     "localhost",
+		SigningKey: pk,
+	}
+
+	grantedAccessList := make([]auth.Access, 0, 0)
+	token, err := tokenIssuer.CreateJWT("test", "test", grantedAccessList)
+
+	tokens := strings.Split(token, ".")
+
+	if len(token) == 0 {
+		t.Fatal("token not generated.")
+	}
+
+	json, err := decodeJWT(tokens[1])
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !strings.Contains(json, "test") {
+		t.Fatal("Valid token was not generated.")
+	}
+
+}
+
+func decodeJWT(rawToken string) (string, error) {
+	data, err := joseBase64Decode(rawToken)
+	if err != nil {
+		return "", errors.New("Error in Decoding base64 String")
+	}
+	return data, nil
+}
+
+func joseBase64Decode(s string) (string, error) {
+	switch len(s) % 4 {
+	case 0:
+	case 2:
+		s += "=="
+	case 3:
+		s += "="
+	default:
+		{
+			return "", errors.New("Invalid base64 String")
+		}
+	}
+	data, err := base64.StdEncoding.DecodeString(s)
+	if err != nil {
+		return "", err //errors.New("Error in Decoding base64 String")
+	}
+	return string(data), nil
+}