assertNull("Null should return null", result);
    }

    /**
     * Test encode/decode round trip with various data
     *
     * @throws Exception
     */
    public void testEncodeDecode_RoundTrip() throws Exception {
        // Test with ASCII text
        final String text = "Hello, World!";
        final byte[] textBytes = text.getBytes("UTF-8");
        final String encoded = Base64Util.encode(textBytes);