### Question:
ForwardingNameResolver extends NameResolver { @Override public void start(Listener listener) { delegate.start(listener); } ForwardingNameResolver(NameResolver delegate); @Override String getServiceAuthority(); @Override void start(Listener listener); @Override void shutdown(); @Override void refresh(); @Override String toString();  }### Answer:
@Test public void start() { NameResolver.Listener listener = new NameResolver.Listener() { @Override public void onAddresses(List<EquivalentAddressGroup> servers, Attributes attributes) { } @Override public void onError(Status error) { } @Override public Object getArgument() { return null; } @Override public void setArgument(Object argument) { } @Override public void removeInvalidCacheSubchannels(Set<String> removeHostPorts) { } }; forwarder.start(listener); verify(delegate).start(listener); }