@Test
public void parseFileExtension() throws Exception {

    String ext0 = FileUtil.parseFileExtension("app.208-05-01.log");
    Assert.assertEquals("log", ext0);
    ext0 = FileUtil.parseFileExtension("app.208-05-01.log.gz");
    Assert.assertEquals("gz", ext0);
    ext0 = FileUtil.parseFileExtension("app.log.gz");
    Assert.assertEquals("gz", ext0);
    ext0 = FileUtil.parseFileExtension("app");
    Assert.assertEquals(null, ext0);
    ext0 = FileUtil.parseFileExtension("app.");
    Assert.assertEquals(null, ext0);
    ext0 = FileUtil.parseFileExtension(".");
    Assert.assertEquals(null, ext0);
    ext0 = FileUtil.parseFileExtension("");
    Assert.assertEquals(null, ext0);
    ext0 = FileUtil.parseFileExtension(null);
    Assert.assertEquals(null, ext0);
}