function testTree_Unaffected() {
  var treeBefore =
      'select(value_pred(DummyTable.boolean eq false))\n' +
      '-select(value_pred(DummyTable.number gt 100))\n' +
      '--select(value_pred(DummyTable.string2 eq OtherStringValue))\n' +
      '---table_access(DummyTable)\n';

  var constructTree = function() {
    var queryContext = new lf.query.SelectContext(hr.db.getSchema());
    queryContext.from = [dt];
    queryContext.where = lf.op.and(
        dt.boolean.eq(false),
        dt.number.gt(100),
        dt.string2.eq('OtherStringValue'));

    var selectNode1 = createSelectStep(queryContext, 0);
    var selectNode2 = createSelectStep(queryContext, 1);
    var selectNode3 = createSelectStep(queryContext, 2);
    var tableAccessNode = new lf.proc.TableAccessFullStep(
        hr.db.getGlobal(), queryContext.from[0]);
    selectNode1.addChild(selectNode2);
    selectNode2.addChild(selectNode3);
    selectNode3.addChild(tableAccessNode);

    return {
      queryContext: queryContext,
      root: selectNode1
    };
  };

  lf.testing.treeutil.assertTreeTransformation(
      constructTree(), treeBefore, treeBefore, pass);
}
Tests a tree where
 - two cross-column indices exist, each index is indexing two columns.
 - a predicate that refers to a subset of the cross column index's columns
   exists. The referred columns are not enough to leverage the index, since
   they don't form a prefix. Cross-column indices exist on
   ['string', 'number'] and ['integer', 'string2'], but only 'number' and
   'string2' are bound with a predicate.
 - a predicate that refers to a non-indexed column ('boolean') exists.

 It ensures that the tree remains unaffected since no index can be leveraged.