### Question:
RangeHeader { public static boolean isValid(String rangeHeader) { if(StringUtils.isBlank(rangeHeader)) { return false; } return rangeHeader.matches("^bytes=\\d*-\\d*(,\\s*\\d*-\\d*)*$"); }  static boolean isValid(String rangeHeader); static Range<Long> parse(String rangeHeader, Long inclusiveUpperBound);  }### Answer:
@Test public void is_valid() { assertThat(RangeHeader.isValid(null)).isFalse(); assertThat(RangeHeader.isValid("")).isFalse(); assertThat(RangeHeader.isValid(" ")).isFalse(); assertThat(RangeHeader.isValid("x")).isFalse(); assertThat(RangeHeader.isValid("x=")).isFalse(); assertThat(RangeHeader.isValid("bytes=1-")).isTrue(); assertThat(RangeHeader.isValid("bytes=200-1000,2000-6576,19000-")).isTrue(); assertThat(RangeHeader.isValid("bytes=200-1000, 2000-6576, 19000-")).isTrue(); }