### Question:
TreeExplorer implements IsWidget { @PreDestroy public void destroy() { destroyView(); selectedItemCanvasUuid = null; canvasHandler = null; } @Inject  TreeExplorer(final ChildrenTraverseProcessor childrenTraverseProcessor,
                        final TextPropertyProviderFactory textPropertyProviderFactory,
                        final Event<CanvasSelectionEvent> selectionEvent,
                        final DefinitionUtils definitionUtils,
                        final ShapeManager shapeManager,
                        final DOMGlyphRenderers domGlyphRenderers,
                        final @Any ManagedInstance<View> views); @SuppressWarnings("unchecked") void show(final CanvasHandler canvasHandler); void clear(); @PreDestroy void destroy(); @Override Widget asWidget(); CanvasHandler getCanvasHandler();  }### Answer:
@Test public void testDestroy() { testedTree.show(canvasHandler); testedTree.destroy(); verify(view, times(1)).destroy(); }