### Question:
Rental { @Override public int hashCode() { int result = initialized ? id : 0; result = result * 19 + movie.hashCode(); result = result * 19 + user.hashCode(); return result; } Rental(IUser aUser, Movie aMovie, int nofRentalDays); private  Rental(IUser aUser, Movie aMovie, int nofRentalDays, Date rentaldate); static Rental createRentalFromDb(IUser aUser, Movie aMovie, int nofRentalDays, Date rentalDate); int calcRemainingDaysOfRental(Date date); double getRentalFee(); int getId(); Movie getMovie(); IUser getUser(); Date getRentalDate(); int getRentalDays(); void setId(int anId); void setRentalDays(int nofRentalDays); @Override boolean equals(Object o); @Override int hashCode();  }### Answer:
@Test public void testHashCode() { Rental x = new Rental(u1, m1, 5); m1.setRented(false); Rental y = new Rental(u1, m1, 5); assertEquals(x.hashCode(), y.hashCode()); x.setId(42); assertTrue(x.hashCode() != y.hashCode()); y.setId(42); assertEquals(x.hashCode(), y.hashCode()); x.setMovie(m2); assertTrue(x.hashCode() != y.hashCode()); y.setMovie(m2); assertEquals(x.hashCode(), y.hashCode()); x.setUser(u2); assertTrue(x.hashCode() != y.hashCode()); y.setUser(u2); assertEquals(x.hashCode(), y.hashCode()); }