### Question:
DMNGridLayer extends DefaultGridLayer { @Override protected GridWidgetDnDMouseUpHandler getGridWidgetDnDMouseUpHandler() { return new DMNGridWidgetDnDMouseUpHandler(this, getGridWidgetHandlersState()); }  void setDefaultTransformMediator(final TransformMediator defaultTransformMediator); @Override //This is overridden as Lienzo calls to draw() when the LienzoPanel is resized //which causes flickering of the 'ghosting' when an Expression type is selected //from the UndefinedExpressionGrid. Layer draw(); @Override Layer batch(); @Override TransformMediator getDefaultTransformMediator(); @Override void exitPinnedMode(final Command onCompleteCommand); @Override void updatePinnedContext(final GridWidget gridWidget); @Override void select(final GridWidget selectedGridWidget); @Override void deregister(final GridWidget gridWidget); @Override Layer removeAll();  }### Answer:
@Test public void checkGridWidgetDnDMouseUpHandler() { assertTrue(gridLayer.getGridWidgetDnDMouseUpHandler() instanceof DMNGridWidgetDnDMouseUpHandler); }