@Test
public void testAssignForInvalidHostGroup() {

  Map<String, List<String>> map = singletonMap("group1", asList("host", "host2"));
  ReflectionTestUtils.setField(clusterCommands, "hostGroups", map);
  when(client.getHostNames()).thenReturn(singletonMap("host3", "HEALTHY"));
  String result = clusterCommands.assign(new Host("host3"), "group0");
  assertEquals("group0 is not a valid host group", result);
}