### Question:
GroupTemplate extends AbstractYammerOperations implements GroupOperations { public void joinGroup(long groupId){ restTemplate.postForObject(buildUri("group_memberships.json", "group_id", String.valueOf(groupId)), null, String.class); } GroupTemplate(RestTemplate restTemplate); List<Group> getGroups(int page, Character letter, String sortBy, boolean reverse); Group getGroup(long groupId); void createGroup(String name, boolean isPrivate); void updateGroup(long groupId, String name, boolean isPrivate); void joinGroup(long groupId); void leaveGroup(long groupId);  }### Answer:
@Test public void testJoinGroup(){ mockServer.expect(requestTo("https: .andExpect(method(POST)) .andRespond(withSuccess("", MediaType.TEXT_PLAIN)); yammerTemplate.groupOperations().joinGroup(1234L); }