### Question:
InputClauseColumn extends DMNSimpleGridColumn<DecisionTableGrid, String> implements HasSingletonDOMElementResource { @Override public void destroyResources() { super.destroyResources(); factory.destroyResources(); } InputClauseColumn(final HeaderMetaData headerMetaData,
                             final TextAreaSingletonDOMElementFactory factory,
                             final double width,
                             final DecisionTableGrid gridWidget);  InputClauseColumn(final List<HeaderMetaData> headerMetaData,
                             final TextAreaSingletonDOMElementFactory factory,
                             final double width,
                             final DecisionTableGrid gridWidget); @Override void edit(final GridCell<String> cell,
                     final GridBodyCellRenderContext context,
                     final Consumer<GridCellValue<String>> callback); @Override void flush(); @Override void destroyResources(); @Override void setWidth(final double width);  }### Answer:
@Test public void checkHeaderDOMElementsAreDestroyed() { final MockHasDOMElementResourcesHeaderMetaData mockHeaderMetaData = mock(MockHasDOMElementResourcesHeaderMetaData.class); column.getHeaderMetaData().add(mockHeaderMetaData); column.destroyResources(); verify(mockHeaderMetaData).destroyResources(); }