### Question:
UndefinedExpressionColumn extends DMNGridColumn<UndefinedExpressionGrid, String> { @Override public void destroyResources() { super.destroyResources(); undefinedExpressionSelector.hide(); } UndefinedExpressionColumn(final double width,
                                     final UndefinedExpressionGrid gridWidget,
                                     final CellEditorControlsView.Presenter cellEditorControls,
                                     final UndefinedExpressionSelectorPopoverView.Presenter undefinedExpressionSelector);  UndefinedExpressionColumn(final List<HeaderMetaData> headerMetaData,
                                     final double width,
                                     final UndefinedExpressionGrid gridWidget,
                                     final CellEditorControlsView.Presenter cellEditorControls,
                                     final UndefinedExpressionSelectorPopoverView.Presenter undefinedExpressionSelector); @Override @SuppressWarnings("unchecked") void edit(final GridCell<String> cell,
                     final GridBodyCellEditContext context,
                     final Consumer<GridCellValue<String>> callback); @Override void setWidth(final double width); @Override void destroyResources(); static final double DEFAULT_WIDTH; }### Answer:
@Test public void testDestroyResources() { column.destroyResources(); verify(undefinedExpressionSelector).hide(); }