assertEquals( Interval.valueOf( 0, 1 ), differenceIterator.intervalIterator().nextInterval() );
assertFalse( differenceIterator.intervalIterator().hasNext() );
assertEquals( 1, differenceIterator.nextDocument() );
assertEquals( 1, differenceIterator.document() );
assertEquals( Interval.valueOf( 2, 3 ), differenceIterator.intervalIterator().nextInterval() );
assertFalse( differenceIterator.intervalIterator().hasNext() );
assertEquals( 2, differenceIterator.nextDocument() );
assertEquals( 2, differenceIterator.document() );
assertEquals( Interval.valueOf( 0, 1 ), differenceIterator.intervalIterator().nextInterval() );
assertEquals( Interval.valueOf( 1, 2 ), differenceIterator.intervalIterator().nextInterval() );
assertEquals( Interval.valueOf( 2, 3 ), differenceIterator.intervalIterator().nextInterval() );