function testExec_Stddev_NullRows() {
  var tableB = schemaWithNullable.table('TableB');
  var inputRelation = lf.proc.Relation.fromRows(
      nullableGenerator.sampleTableBRows, [tableB.getName()]);
  return checkCalculationForRelation(
      inputRelation, lf.fn.stddev(tableB['id']),
      null, checkEquals);
}
Tests for Stddev on TableB which has only null values for the column.
@return {!IThenable}