function testSingleOrPredicate() {
  var treeBefore =
      'project()\n' +
      '-select(combined_pred_or)\n' +
      '--table_access(Employee)\n';

  var treeAfter =
      'project()\n' +
      '-table_access_by_row_id(Employee)\n' +
      '--multi_index_range_scan()\n' +
      '---index_range_scan(Employee.pkEmployee, [100, 100], natural)\n' +
      '---index_range_scan(Employee.idx_salary, [200, 200], natural)\n';

  var tree = constructTreeWithPredicates(
      [lf.op.or(e['id'].eq(100), e['salary'].eq(200))]);
  lf.testing.treeutil.assertTreeTransformation(
      tree, treeBefore, treeAfter, pass);
}
Tests a simple tree, where only one OR predicate exists and it can leverage
indices.