### Question:
IntRangeUtil { public static int requireZero(int val) { if (val != 0) { throw new IllegalArgumentException(val + IS_NOT_ZERO); } return val; } private  IntRangeUtil(); static int requirePositive(int val); static int requireNegative(int val); static int requireZero(int val); static int requireNonPositive(int val); static int requireNonNegative(int val); static int requireNonZero(int val); static int requireEquals(int val, int otherVal); static int requireNotEquals(int val, int otherVal); static int requireInRange(int val, int first, int lastExclusive); static int requireInRangeClosed(int val, int first, int lastInclusive); static int requirePositive(int val, Function<String, E> exceptionConstructor); static int requireNegative(int val, Function<String, E> exceptionConstructor); static int requireZero(int val, Function<String, E> exceptionConstructor); static int requireNonPositive(int val, Function<String, E> exceptionConstructor); static int requireNonNegative(int val, Function<String, E> exceptionConstructor); static int requireNonZero(int val, Function<String, E> exceptionConstructor); static int requireEquals(int val, int otherVal, Function<String, E> exceptionConstructor); static int requireNotEquals(int val, int otherVal, Function<String, E> exceptionConstructor); static int requireInRange(int val, int first, int lastExclusive, Function<String, E> exceptionConstructor); static int requireInRangeClosed(int val, int first, int lastInclusive, Function<String, E> exceptionConstructor);  }### Answer:
@Test void requireZero() { testHelper(IS_ZERO, IntRangeUtil::requireZero); }
@Test void testRequireZero() { assertEquals(0, IntRangeUtil.requireZero(0, RuntimeException::new)); }
@Test void testRequireZero2() { assertThrows(RuntimeException.class, () -> IntRangeUtil.requireZero(1, RuntimeException::new)); }
@Test void testRequireZero3() { assertThrows(RuntimeException.class, () -> IntRangeUtil.requireZero(-1, RuntimeException::new)); }