### Question:
TimestampDataConverter implements DataConverter<Timestamp>, DateParser<Timestamp> { @Override public String dateToString(Timestamp value) { return value != null ? getDateFormatter().format(value) : ""; }  @Override Timestamp stringToValue(String rawData); @Override String valueToString(Timestamp value); @Override Timestamp parsDate(String rawData); @Override String dateToString(Timestamp value); static DateFormat getDateFormatWithTimeZone(DateFormat dateFormat);  }### Answer:
@Test public void dateToString_valueIsNull_returnNull() { assertEquals(timestampDataConverter.dateToString(null), ""); }
@Test public void dateToString_valueIsTimestamp_returnString() { assertEquals(timestampDataConverter.dateToString(Timestamp.valueOf("2018-05-11 00:00:00")), "2018-05-11"); }