}
	for _, tt := range tests {
		got, err := parseHexUint([]byte(tt.in))
		if tt.wantErr != "" {
			if err != nil && !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("parseHexUint(%q) = %v, %v; want error %q", tt.in, got, err, tt.wantErr)
			}
		} else {
			if err != nil || got != tt.want {
				t.Errorf("parseHexUint(%q) = %v, %v; want %v", tt.in, got, err, tt.want)
			}
		}
	}

func parseChunkSignature(chunk []byte) []byte {
	chunkSplits := bytes.SplitN(chunk, []byte(s3ChunkSignatureStr), 2)
	return chunkSplits[1]
}

// parse hex to uint64.
func parseHexUint(v []byte) (n uint64, err error) {
	for i, b := range v {
		switch {
		case '0' <= b && b <= '9':
			b -= '0'
		case 'a' <= b && b <= 'f':
			b = b - 'a' + 10
		case 'A' <= b && b <= 'F':