function testExec_ValidProjectionList() {
  var e = db.getSchema().getEmployee();

  // Constructing a query where all requested columns are aggregated.
  var query1 = new lf.query.SelectBuilder(
      hr.db.getGlobal(), [lf.fn.min(e.salary), lf.fn.avg(e.salary)]);
  query1.from(e);

  // Constructing a query where all requested columns are non-aggregated.
  var query2 = new lf.query.SelectBuilder(
      hr.db.getGlobal(), [e.salary, e.salary]);
  query2.from(e);

  return goog.Promise.all([
    query1.exec(),
    query2.exec()
  ]);
}
Tests that constructing a query succeeds if a valid projection list is
requested (and if no other violation occurs).
@return {!IThenable}