### Question:
DateUtil { public static Date parseIso8601DateTime(String dateStr) { try { return new DateTime(dateStr).toDate(); } catch(Exception e) { return null; } } private  DateUtil(); static Date parseRfc1123Date(String dateStr); static Date parseIso8601DateTime(String dateStr); static String formatIso8601Date(Date date); static String formatIso8601Date(long time); static String formatRfc1123Date(Date date); static String formatRfc1123Date(long timeStamp);  }### Answer:
@Test public void parseMalformedIso8691() { assertNull(DateUtil.parseIso8601DateTime("invalid date format")); }