### Question:
ClearCanvasCommand extends AbstractCanvasCommand { @Override public CommandResult<CanvasViolation> undo(final AbstractCanvasHandler context) { throw new UnsupportedOperationException("Undo operation for Clear Canvas Command is still not supported."); }  @Override CommandResult<CanvasViolation> execute(final AbstractCanvasHandler context); @Override CommandResult<CanvasViolation> undo(final AbstractCanvasHandler context); @Override String toString();  }### Answer:
@Test(expected = UnsupportedOperationException.class) public void testUndo() { tested.undo(canvasHandler); }