### Question:
ActionCollection { @SuppressWarnings("unchecked") public void enableAction(Class actionClass, boolean enable) throws IllegalArgumentException { if (actionClass == null) { throw new IllegalArgumentException("null Action Class passed."); } final Action action = get(actionClass); if (action != null) { action.setEnabled(enable); } } ActionCollection(IApplication app); void add(Action action); synchronized Action get(Class<? extends Action> actionClass); synchronized Action get(String actionClassName); @SuppressWarnings("unchecked") void enableAction(Class actionClass, boolean enable); void internalFrameOpenedOrClosed(int nbrInternalFramesOpen); void deactivationChanged(IWidget frame); synchronized void activationChanged(IWidget frame); synchronized void loadActionKeys(ActionKeys[] actionKeys); Iterator<Action> actions(); synchronized void setCurrentSession(ISession session);  }### Answer:
@Test (expected = IllegalArgumentException.class ) public final void testEnableAction() { actionCollectionUnderTest.enableAction(null, true); }