### Question:
RandomGeneratorImpl implements RandomGenerator { @Override public List<Character> randLowerCaseChars(int num) { if (num <= 0) throw new IllegalArgumentException(); Character [] chars = new Character[num]; for (int i = 0; i < num; i++) { chars[i] = randLowerCaseChar(); } return Arrays.asList(chars); }  @Override char randLowerCaseChar(); @Override char randUpperCaseChar(); @Override char randChar(); @Override List<Character> randLowerCaseChars(int num); @Override List<Character> randUpperCaseChars(int num); @Override List<Character> randChars(int num); @Override int randInt(int lowBound, int upBound); @Override List<Integer> randIntegers(int lowBount, int upBount, int length); @Override String randString(int charCount, int intCount, boolean mustSeartWithAlph); @Override List<String> randStrings(int size, int alphNum, int digitNum, boolean mustStartWithAlph); @Override double randDouble(double lowBound, double upBound); @Override List<Double> randDoubles(int size, double lowBound, double upBound); @Override boolean randBoolean();  }### Answer:
@Test public void randLowerCaseChars() throws Exception { int iter = 1000; List<Character> chars = randomGenerator.randLowerCaseChars(iter); chars.forEach(c -> assertTrue(c >= 'a' && c <= 'z')); }