  @Test(expected = NullPointerException.class)
  public void mkeysOfnWithNullSubConditionsList() {

    try {
      ThresholdFactory.constructMOfNCondition(1, 2, null);
    } catch (NullPointerException e) {
      assertThat(e.getMessage(), is("subconditions must not be null!"));
      throw e;
    }
  }