function testTree_TableAccess_CrossColumnIndex_Natural() {
  var treeBefore =
      'project()\n' +
      '-order_by(CrossColumnTable.string ASC, CrossColumnTable.number ASC)\n' +
      '--select(value_pred(CrossColumnTable.boolean eq false))\n' +
      '---table_access(CrossColumnTable)\n';

  var treeAfter =
      'project()\n' +
      '-select(value_pred(CrossColumnTable.boolean eq false))\n' +
      '--table_access_by_row_id(CrossColumnTable)\n' +
      '---index_range_scan(CrossColumnTable.idx_crossColumn, ' +
          '[unbound, unbound],[unbound, unbound], natural)\n';

  lf.testing.treeutil.assertTreeTransformation(
      constructTree2(lf.Order.ASC, lf.Order.ASC), treeBefore, treeAfter, pass);
}
Tests the case where a cross-column index can be leveraged to perform the
ORDER BY, using the index's natural order.