### Question:
StandardCategorySeriesLabelGenerator implements
    CategorySeriesLabelGenerator, Cloneable, PublicCloneable, Serializable { @Override public String generateLabel(CategoryDataset dataset, int series) { if (dataset == null) { throw new IllegalArgumentException("Null 'dataset' argument."); } String label = MessageFormat.format(this.formatPattern, createItemArray(dataset, series)); return label; } StandardCategorySeriesLabelGenerator();  StandardCategorySeriesLabelGenerator(String format); @Override String generateLabel(CategoryDataset dataset, int series); @Override Object clone(); @Override boolean equals(Object obj); @Override int hashCode(); static final String DEFAULT_LABEL_FORMAT; }### Answer:
@Test public void testGenerateLabel() { StandardCategorySeriesLabelGenerator g = new StandardCategorySeriesLabelGenerator("{0}"); DefaultCategoryDataset dataset = new DefaultCategoryDataset(); dataset.addValue(1.0, "R0", "C0"); dataset.addValue(2.0, "R0", "C1"); dataset.addValue(3.0, "R1", "C0"); dataset.addValue(null, "R1", "C1"); String s = g.generateLabel(dataset, 0); assertEquals("R0", s); }