for ( int i = 1; i <= element_count; i++ ) {
a.add( i );
}
a.reverse();
a.sort( 5, 15 );
int[] expected = {20, 19, 18, 17, 16, 6, 7, 8, 9, 10,
11, 12, 13, 14, 15, 5, 4, 3, 2, 1};
for ( int i = 0; i < a.size(); i++ ) {
assertEquals( expected[i], a.get( i ) );