### Question:
GroupsServiceImpl extends BaseApiService<CloudIdentity> implements GroupsService { @Override public ListenableFuture<Operation> deleteGroup(String groupId) throws IOException { validateGroupResourceName(groupId); Groups.Delete delete = service.groups().delete(groupId); return batchRequest(delete, retryPolicy, batchService); } private  GroupsServiceImpl(Builder builder); @Override ListenableFuture<Operation> createGroup(Group group); @Override ListenableFuture<Group> getGroup(String groupId); @Override ListenableFuture<Operation> deleteGroup(String groupId); @Override ListenableFuture<Operation> createMembership(String groupId, Membership member); @Override ListenableFuture<Membership> getMembership(String memberId); @Override ListenableFuture<Operation> deleteMembership(String memberId); @Override Iterable<Group> listGroups(String groupNamespace); @Override Iterable<Membership> listMembers(String groupId); static GroupsServiceImpl fromConfiguration(CredentialFactory credentialFactory);  }### Answer:
@Test public void testDeleteGroup() throws Exception { String groupId = "groups/id1"; Groups.Delete deleteRequest = mock(Groups.Delete.class); when(groups.delete(groupId)).thenReturn(deleteRequest); Operation operation = new Operation().setDone(true); doAnswer( invocation -> { AsyncRequest<Operation> input = invocation.getArgument(0); setAsyncRequestResponse(input, operation); return null; }) .when(batchRequestService) .add(any()); ListenableFuture<Operation> delete = groupsService.deleteGroup(groupId); assertEquals(operation, delete.get()); }