public void testRemoveContainer() throws Exception {
config.newTransaction().addContainer(EXTRA_CONTAINER).commit();
config.newTransaction().addContainer(EXTRA_CONTAINER).commit();
ConfigObserver observer = EasyMock.createMock(ContainerConfig.ConfigObserver.class);
observer.containersChanged(EasyMock.isA(ContainerConfig.class),
EasyMock.eq(ImmutableSet.<String>of()), EasyMock.eq(ImmutableSet.of("extra")));
EasyMock.replay(observer);
config.addConfigObserver(observer, false);
config.newTransaction().removeContainer("extra").commit();