### Question:
DateTimes { public static DateTime toDateTime(Calendar calendar) { return dateTimesHelper.toDateTime(calendar); } private  DateTimes(); static DateTime toDateTime(Calendar calendar); static DateTime toDateTime(Instant instant, String timeZoneId); static DateTime toDateTime(org.joda.time.DateTime dateTime); static DateTime toDateTime(String dateTime, String timeZoneId); static DateTime toDateTimeWithTimeZone(String dateTime); static org.joda.time.DateTime toDateTime(DateTime dateTime); static Calendar toCalendar(DateTime dateTime); static Calendar toCalendar(DateTime dateTime, Locale locale); static String toString(Date date); static String toString(DateTime dateTime); static String toStringWithTimeZone(DateTime dateTime); static String toStringForTimeZone(DateTime dateTime, String newZoneId);  }### Answer:
@Test public void testTransitive_apiJodaApi() { assertEquals(apiDateTime1, DateTimes.toDateTime(DateTimes.toDateTime(apiDateTime1))); assertEquals(apiDateTime2, DateTimes.toDateTime(DateTimes.toDateTime(apiDateTime2))); assertEquals(apiDateTime3, DateTimes.toDateTime(DateTimes.toDateTime(apiDateTime3))); }
@Test public void testTransitive_jodaApiJoda() { assertEquals(jodaDateTime1, DateTimes.toDateTime(DateTimes.toDateTime(jodaDateTime1))); assertEquals(jodaDateTime2, DateTimes.toDateTime(DateTimes.toDateTime(jodaDateTime2))); assertEquals(jodaDateTime3, DateTimes.toDateTime(DateTimes.toDateTime(jodaDateTime3))); }
@Test public void testTransitive_calendarApiJoda() { assertEquals(jodaDateTime1, DateTimes.toDateTime(DateTimes.toDateTime(calendar1))); assertEquals(jodaDateTime2, DateTimes.toDateTime(DateTimes.toDateTime(calendar2))); assertEquals(jodaDateTime3, DateTimes.toDateTime(DateTimes.toDateTime(calendar3))); }
@Test public void testTransitive_stringApiJoda() { assertEquals( jodaDateTime1, DateTimes.toDateTime(DateTimes.toDateTime(stringDateTime1, TIME_ZONE_ID1))); assertEquals( jodaDateTime2, DateTimes.toDateTime(DateTimes.toDateTime(stringDateTime2, TIME_ZONE_ID2))); assertEquals( jodaDateTime3, DateTimes.toDateTime(DateTimes.toDateTime(stringDateTime3, TIME_ZONE_ID3))); }
@Test public void testTransitive_instantApiJoda() { assertEquals( jodaDateTime1, DateTimes.toDateTime(DateTimes.toDateTime(jodaDateTime1.toInstant(), TIME_ZONE_ID1))); assertEquals( jodaDateTime2, DateTimes.toDateTime(DateTimes.toDateTime(jodaDateTime2.toInstant(), TIME_ZONE_ID2))); assertEquals( jodaDateTime3, DateTimes.toDateTime(DateTimes.toDateTime(jodaDateTime3.toInstant(), TIME_ZONE_ID3))); }
@Test public void testToDateTime_fromCalendarToApiDateTime() { assertEquals(apiDateTime1, DateTimes.toDateTime(calendar1)); assertEquals(apiDateTime2, DateTimes.toDateTime(calendar2)); assertEquals(apiDateTime3, DateTimes.toDateTime(calendar3)); }
@Test public void testToDateTime_fromStringToApiDateTime() { assertEquals(apiDateTime1, DateTimes.toDateTime(stringDateTime1, TIME_ZONE_ID1)); assertEquals(apiDateTime2, DateTimes.toDateTime(stringDateTime2, TIME_ZONE_ID2)); assertEquals(apiDateTime3, DateTimes.toDateTime(stringDateTime3, TIME_ZONE_ID3)); }
@Test public void testToDateTime_fromApiDateTimeToJoda() { assertEquals(jodaDateTime1, DateTimes.toDateTime(apiDateTime1)); assertEquals(jodaDateTime2, DateTimes.toDateTime(apiDateTime2)); assertEquals(jodaDateTime3, DateTimes.toDateTime(apiDateTime3)); }
@Test public void testToDateTime_fromInstantToApiDateTime() { assertEquals(apiDateTime1, DateTimes.toDateTime(jodaDateTime1.toInstant(), TIME_ZONE_ID1)); assertEquals(apiDateTime2, DateTimes.toDateTime(jodaDateTime2.toInstant(), TIME_ZONE_ID2)); assertEquals(apiDateTime3, DateTimes.toDateTime(jodaDateTime3.toInstant(), TIME_ZONE_ID3)); }