### Question:
Configuration implements Iterable<PeerId>, Copiable<Configuration> { @Override public Configuration copy() { return new Configuration(this.peers, this.learners); } Configuration();  Configuration(final Iterable<PeerId> conf);  Configuration(final Configuration conf);  Configuration(final Iterable<PeerId> conf, final Iterable<PeerId> learners); void setLearners(final LinkedHashSet<PeerId> learners); boolean addLearner(final PeerId learner); int addLearners(final Iterable<PeerId> learners); boolean removeLearner(final PeerId learner); LinkedHashSet<PeerId> getLearners(); List<PeerId> listLearners(); @Override Configuration copy(); boolean isValid(); void reset(); boolean isEmpty(); int size(); @Override Iterator<PeerId> iterator(); Set<PeerId> getPeerSet(); List<PeerId> listPeers(); List<PeerId> getPeers(); void setPeers(final List<PeerId> peers); void appendPeers(final Collection<PeerId> set); boolean addPeer(final PeerId peer); boolean removePeer(final PeerId peer); boolean contains(final PeerId peer); @Override int hashCode(); @Override boolean equals(final Object obj); @Override String toString(); boolean parse(final String conf); void diff(final Configuration rhs, final Configuration included, final Configuration excluded);  }### Answer:
@Test public void testCopy() { final Configuration conf = JRaftUtils.getConfiguration("localhost:8081,localhost:8082,localhost:8083"); final Configuration copied = conf.copy(); assertEquals(conf, copied); assertNotSame(conf, copied); assertEquals(copied.size(), 3); assertEquals("localhost:8081,localhost:8082,localhost:8083", copied.toString()); final PeerId newPeer = new PeerId("localhost", 8084); conf.addPeer(newPeer); assertEquals(copied.size(), 3); assertEquals(conf.size(), 4); assertTrue(conf.contains(newPeer)); assertFalse(copied.contains(newPeer)); }