public void hasLength(int expectedLength) {
    checkArgument(expectedLength >= 0, "expectedLength(%s) must be >= 0", expectedLength);
    check("length()").that(checkNotNull(actual).length()).isEqualTo(expectedLength);
  }
@Test
  public void hasLengthNegative() {
    try {
      assertThat("kurt").hasLength(-1);
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }