  The generalized test ideals introduced in [HY] are related to multiplier
ideals via reduction to characteristic p. In addition, they satisfy many of the
subtle properties of the multiplier ideals, which in characteristic zero follow
via vanishing theorems. In this note we give several examples to emphasize the
different behavior of test ideals and multiplier ideals. Our main result is
that every ideal in an F-finite regular local ring can be written as a
generalized test ideal. We also prove the semicontinuity of $F$-pure thresholds
(though the analogue of the Generic Restriction Theorem for multiplier ideals
does not hold).
