### Question:
MaterialOptionHelper extends AbstractOptionHelper { @Override public ChartOptions addTitle(ChartOptions parent, String title) { ChartOptions chartOpt = new ChartOptions(); chartOpt.put("title", title); parent.put("chart", chartOpt); return parent; } MaterialOptionHelper(Chart chart); @Override ChartOptions addTitle(ChartOptions parent, String title); @Override ChartOptions addTitle(ChartOptions parent, IModel<String> titleModel); @Override ChartOptions addSubTitle(ChartOptions parent, String subTitle); @Override ChartOptions addSubTitle(ChartOptions parent, IModel<String> subTitleModel); @Override ChartOptions addDualAxisOptions(ChartOptions parent,
            String[] axisNames, String[] seriesMapping, String[] axisTitles,
            OptionModifier[] axisModifiers, OptionModifier[] seriesModifiers);  }### Answer:
@Test public void testAddTitleOption() { ChartOptions parent = new ChartOptions(); MaterialOptionHelper instance = new MaterialOptionHelper(chart); String expResult = "{\"chart\":{\"title\":\"Chart Title\"}}"; ChartOptions result = instance.addTitle(parent, "Chart Title"); assertEquals(expResult, result.toJSON().toString()); }