### Question:
Randoms { public static double randomDouble() { return newRandom().nextDouble(); }  static String randomString(final int length); static char randomChar(); static String randomString(); static String randomEmailAddress(); static String randomPhoneNumber(); static DateTime randomDateTime(); static LocalDateTime randomLocalDateTime(); static LocalDate randomLocalDate(); static LocalTime randomLocalTime(); static E randomEnum(final Class<E> enumClass); static Set<E> randomEnumSet(final Class<E> enumClass); static E randomEnumInSet(final Set<E> enumSet); static Set<T> randomSubset(final Set<T> set); static int randomInt(final int max); static float randomFloat(); static double randomDouble(); static long randomLong(); static boolean randomBoolean(); static BigDecimal randomBigDecimal(final int maxValue, final int precision); static BigDecimal randomPositiveBigDecimal(final int maxValue, final int precision); static int randomIntInRange(final int from, final int to); static String randomCreditCardNumber(final String prefix); static String randomId(); static T randomItem(final T[] array); static T randomItem(final Collection<T> collection); static Set<String> randomIdSet();  }### Answer:
@Test public void shouldReturnRandomDouble() { final Set<Double> randomDoubles = new HashSet<>(); for (int n = 0; n < SAMPLE_SIZE; n++) { final double randomDouble = Randoms.randomDouble(); randomDoubles.add(randomDouble); } assertEquals("Random sample Doubles should be unique", SAMPLE_SIZE, randomDoubles.size()); }