### Question:
MetaDataEditorWidgetViewImpl extends Composite implements MetaDataEditorWidgetView,
                                                                       HasValue<String> { public boolean isDuplicateAttribute(final String attribute) { return presenter.isDuplicateAttribute(attribute); }  @Override String getValue(); @Override void setValue(final String value); @Override void setValue(final String value,
                         final boolean fireEvents); @Override void doSave(); @Override HandlerRegistration addValueChangeHandler(final ValueChangeHandler<String> handler); boolean isDuplicateAttribute(final String attribute); @Override void init(final Presenter presenter); @Override void setReadOnly(final boolean readOnly); @Override int getMetaDataRowsCount(); @Override void setTableDisplayStyle(); @Override void setNoneDisplayStyle(); @Override void setMetaDataRows(final List<MetaDataRow> rows); @Override List<MetaDataRow> getMetaDataRows(); @Override MetaDataListItemWidgetView getMetaDataWidget(final int index); @EventHandler("addButton") void handleAddButton(final ClickEvent e); @Override void removeMetaData(final MetaDataRow metaDataRow);  }### Answer:
@Test public void testIsDuplicateAttribute() { view.init(presenter); when(presenter.isDuplicateAttribute("test")).thenReturn(false); assertFalse(view.isDuplicateAttribute("test")); verify(presenter, times(1)).isDuplicateAttribute("test"); }