### Question:
DateDetector { public static String getRegexpByDateFormat( String dateFormat ) { return getRegexpByDateFormat( dateFormat, null ); } private  DateDetector(); static String getRegexpByDateFormat( String dateFormat ); static String getRegexpByDateFormat( String dateFormat, String locale ); static String getDateFormatByRegex( String regex ); static String getDateFormatByRegex( String regex, String locale ); static Date getDateFromString( String dateString ); static Date getDateFromString( String dateString, String locale ); static Date getDateFromStringByFormat( String dateString, String dateFormat ); static String detectDateFormat( String dateString ); static String detectDateFormat( String dateString, String locale ); static String detectDateFormatBiased( String dateString, String locale, String desiredKey ); static BidiMap getDateFormatToRegExps( String locale ); static boolean isValidDate( String dateString, String dateFormat ); static boolean isValidDate( String dateString ); static boolean isValidDateFormatToStringDate( String dateFormat, String dateString ); static boolean isValidDateFormatToStringDate( String dateFormat, String dateString, String locale );  }### Answer:
@Test public void testGetRegexpByDateFormat() { assertNull( DateDetector.getRegexpByDateFormat( null ) ); assertEquals( SAMPLE_REGEXP, DateDetector.getRegexpByDateFormat( SAMPLE_DATE_FORMAT ) ); }
@Test public void testGetRegexpByDateFormatLocale() { assertNull( DateDetector.getRegexpByDateFormat( null, null ) ); assertNull( DateDetector.getRegexpByDateFormat( null, LOCALE_en_US ) ); assertNull( DateDetector.getRegexpByDateFormat( SAMPLE_DATE_FORMAT_US ) ); assertEquals( SAMPLE_REGEXP_US, DateDetector.getRegexpByDateFormat( SAMPLE_DATE_FORMAT_US, LOCALE_en_US ) ); }