function checkCalculationWithJoin(aggregatedColumn, expectedValue, assertFn) {
  var relationLeft = lf.proc.Relation.fromRows(
      dataGenerator.sampleEmployees, [e.getName()]);
  var relationRight = lf.proc.Relation.fromRows(
      dataGenerator.sampleJobs, [j.getName()]);
  var joinPredicate = new lf.pred.JoinPredicate(
      e.jobId, j.id, lf.eval.Type.EQ);
  var joinedRelation = joinPredicate.evalRelationsHashJoin(
      relationLeft, relationRight, false);
  return checkCalculationForRelation(
      joinedRelation, aggregatedColumn, expectedValue, assertFn);
}
Checks that performing a transformation on a relationship that is the
result of a natural join, results in a relation with fields that are
populated as expected.
@param {!lf.schema.Column} aggregatedColumn The column to be calculated.
@param {number|!Array<number>} expectedValue The expected value for the
    aggregated column.
@param {!Function} assertFn
@return {!IThenable}