### Question:
VariableListItemWidgetViewImpl implements VariableListItemWidgetView,
                                                       ComboBoxView.ModelPresenter { private boolean isDuplicateName(final String name) { return parentWidget.isDuplicateName(name); }  Set<String> getTagSet(); void setTagSet(Set<String> tagSet); String getPreviousCustomValue(); void setPreviousCustomValue(String previousCustomValue); void setParentWidget(final VariablesEditorWidgetView.Presenter parentWidget); @Override void setTextBoxModelValue(final TextBox textBox,
                                     final String value); @Override void setListBoxModelValue(final ValueListBox<String> listBox,
                                     final String value); @Override String getModelValue(final ValueListBox<String> listBox); @PostConstruct void init(); @Override VariableRow getModel(); @Override void setModel(final VariableRow model); @Override VariableType getVariableType(); @Override String getDataTypeDisplayName(); @Override void setDataTypeDisplayName(final String dataTypeDisplayName); @Override String getCustomDataType(); @Override void setCustomDataType(final String customDataType); @Override void setCustomTags(final List<String> tags); @Override List<String> getCustomTags(); @Override void setDataTypes(final ListBoxValues dataTypeListBoxValues); @Override void setTagTypes(final List<String> tagTypes); @Override void setReadOnly(final boolean readOnly); @EventHandler("deleteButton") void handleDeleteButton(final ClickEvent e); @EventHandler("closeButton") void handleCloseButton(final ClickEvent e); @EventHandler("acceptButton") void handleAcceptButton(final ClickEvent e); @Override void notifyModelChanged(); @Override void setTagsNotEnabled();  }### Answer:
@Test public void testNameChangeHandlerWhenDuplicate() { when(parent.isDuplicateName(VARIABLE_NEW_NAME)).thenReturn(true); prepareNameChange(VARIABLE_NEW_NAME, MODEL_NEW_TO_STRING); verify(parent).isDuplicateName(VARIABLE_NEW_NAME); verify(notification).fire(new NotificationEvent(StunnerFormsClientFieldsConstants.CONSTANTS.DuplicatedVariableNameError(VARIABLE_NEW_NAME), NotificationEvent.NotificationType.ERROR)); verify(name).setValue(VARIABLE_NAME); }