* (NCR). However, horizontal tab {@code '\t'}, line feed {@code '\n'} and carriage return {@code
   * '\r'} are escaped to a corresponding NCR {@code "	"}, {@code "
"}, and {@code "
"}
   * respectively. Any other non-ASCII characters appearing in the input will be preserved in the
   * output.
   *

    // Test all escapes
    assertEquals(
        "a&quot;b&lt;c&gt;d&amp;e&quot;f&apos;", xmlAttributeEscaper.escape("a\"b<c>d&e\"f'"));
    // Test '\t', '\n' and '\r' are escaped.
    assertEquals("a&#x9;b&#xA;c&#xD;d", xmlAttributeEscaper.escape("a\tb\nc\rd"));
  }

  // Helper to assert common properties of xml escapers.
  static void assertBasicXmlEscaper(