FormGroup implements IsElement { public void setValidationState(final ValidationState state) { clearValidationState(); addCSSClass(div, state.getCssName()); }  void clearValidationState(); void setValidationState(final ValidationState state); @Override HTMLElement getElement();  }
@Test public void testSetValidationState() { formGroup.setValidationState(ValidationState.SUCCESS); verify(domTokenList).add(ValidationState.SUCCESS.getCssName()); }