### Question:
Group extends Item { @Modifies( "items" ) public void insertItem(String itemId, String beforeItemId) { if ((beforeItemId == null) || (beforeItemId.length() == 0)) { addItem(itemId); } else if (validItemId(itemId)) { int pos = this.items.indexOf(beforeItemId); if (pos < 0) { addItem(itemId); } else { this.items.add(pos, itemId); } } } Group();  Group(String type);  Group(String type, String label); String getLabel(); void setLabel(String label); String[] getItems(); List<String> getItemList(); @Modifies( "items" ) void setItems(String[] items); @Modifies( "items" ) void addItem(String itemId); @Modifies( "items" ) void insertItem(String itemId, String beforeItemId); @Modifies( "items" ) void appendItem(String itemId, String afterItemId); @Modifies( "items" ) int removeItem(String itemId); @Modifies( "items" ) void setItems(Object[] items); String getItemsAsString(); @Modifies( "items" ) void setItemsAsString(String items); @Override String toString(); @Modifies( { "presentationStyles", "stylesList" } ) void addPresentationStyle(String presentationStyle); @Modifies( { "presentationStyles", "stylesList" } ) void removePresentationStyle(String presentationStyle); static final String COMMA_SEPARATOR; }### Answer:
@Test public void testInsertItemContainingComma() { Group group = new Group(); try { group.insertItem("a,", "b"); fail(); } catch (IllegalArgumentException e) { } }