### Question:
ExpressionContainerGrid extends BaseGrid<Expression> { @Override public void onItemSelected(final ListSelectorItem item) { final ListSelectorTextItem li = (ListSelectorTextItem) item; li.getCommand().execute(); } ExpressionContainerGrid(final DMNGridLayer gridLayer,
                                   final CellEditorControlsView.Presenter cellEditorControls,
                                   final TranslationService translationService,
                                   final ListSelectorView.Presenter listSelector,
                                   final SessionManager sessionManager,
                                   final SessionCommandManager<AbstractCanvasHandler> sessionCommandManager,
                                   final DefaultCanvasCommandFactory canvasCommandFactory,
                                   final Supplier<ExpressionEditorDefinitions> expressionEditorDefinitions,
                                   final Supplier<ExpressionGridCache> expressionGridCache,
                                   final ParameterizedCommand<Optional<Expression>> onHasExpressionChanged,
                                   final ParameterizedCommand<Optional<HasName>> onHasNameChanged,
                                   final Event<RefreshFormPropertiesEvent> refreshFormPropertiesEvent,
                                   final Event<DomainObjectSelectionEvent> domainObjectSelectionEvent); @Override boolean onDragHandle(final INodeXYEvent event); @Override void deselect(); void setExpression(final String nodeUUID,
                              final HasExpression hasExpression,
                              final Optional<HasName> hasName,
                              final boolean isOnlyVisualChangeAllowed); @Override List<ListSelectorItem> getItems(final int uiRowIndex,
                                           final int uiColumnIndex); @Override void onItemSelected(final ListSelectorItem item); Optional<BaseExpressionGrid<? extends Expression, ? extends GridData, ? extends BaseUIModelMapper>> getBaseExpressionGrid(); @Override boolean selectCell(final Point2D ap,
                              final boolean isShiftKeyDown,
                              final boolean isControlKeyDown); @Override boolean selectCell(final int uiRowIndex,
                              final int uiColumnIndex,
                              final boolean isShiftKeyDown,
                              final boolean isControlKeyDown);  }### Answer:
@Test public void testOnItemSelected() { final Command command = mock(Command.class); final HasListSelectorControl.ListSelectorTextItem listSelectorItem = mock(HasListSelectorControl.ListSelectorTextItem.class); when(listSelectorItem.getCommand()).thenReturn(command); grid.onItemSelected(listSelectorItem); verify(command).execute(); }