public static Test suite() {
        TestSuite suite = new TestSuite("org.jfree.chart.renderer");
        suite.addTestSuite(AbstractRendererTests.class);
        suite.addTestSuite(AreaRendererEndTypeTests.class);
        suite.addTestSuite(DefaultPolarItemRendererTests.class);
        suite.addTestSuite(GrayPaintScaleTests.class);
        suite.addTestSuite(LookupPaintScaleTests.class);
        suite.addTestSuite(OutlierTests.class);
        suite.addTestSuite(RendererUtilitiesTests.class);
        return suite;