### Question:
RFC1123 { static RFC1123 instance() { RFC1123 instance = INSTANCES.get(); if ( null == instance ) { instance = new RFC1123(); INSTANCES.set( instance ); } return instance; } private  RFC1123(); Date parse( String input ); String format( Date date ); static Date parseTimestamp( String input ); static String formatDate( Date date ); static final TimeZone GMT; }### Answer:
@Test public void shouldReturnSameInstanceInSameThread() { RFC1123 instance = RFC1123.instance(); RFC1123 instance2 = RFC1123.instance(); assertSame( "Expected to get same instance from second call to RFC1123.instance() in same thread", instance, instance2 ); }