code: @Test public void testSetFeatureState() throws IOException {
    FileBasedStateRepository repo=new FileBasedStateRepository(file);
    repo.setFeatureState(new FeatureState(MyFeature.FEATURE1,false));
    repo.setFeatureState(new FeatureState(MyFeature.FEATURE2,true,Arrays.asList("a","b","c")));
    FileInputStream fis=new FileInputStream(file);
    Properties p=new Properties();
    p.load(fis);
    assertEquals(4,p.size());
    assertEquals("false",p.getProperty("FEATURE1"));
    assertEquals("true",p.getProperty("FEATURE2"));
    assertEquals("a,b,c",p.getProperty("FEATURE2.users"));
    assertEquals("true",p.getProperty("FEATURE3"));
  }
  