@Test
  public void testDefaultInvalid() {
    final TimestampParser tsp = new TimestampParser();
    Assert.assertNull(tsp.parseTimestamp("12345"));
    Assert.assertNull(tsp.parseTimestamp("1945-12-45 23:59:59"));
    Assert.assertNull(tsp.parseTimestamp("1945-15-20 23:59:59"));
    Assert.assertNull(tsp.parseTimestamp("0000-00-00 00:00:00"));
    Assert.assertNull(tsp.parseTimestamp(""));
    Assert.assertNull(tsp.parseTimestamp("null"));
  }
No timestamp patterns, should default to normal timestamp format.

@see Timestamp#valueOf(String)
common/src/test/org/apache/hive/common/util/TestTimestampParser.java