this is my first time i use Jest for testing so when I tried to run my unit test it fail because the import of communicationManagerService (actualy it call the coreManager.MessageSubject which is not used in my OutCallManager class)
this is my class :

import {Inject, Injectable} from '@nestjs/common';

import {CommunicationManagerService} from 'package/communication-manager';
import {ManagerLogger} from '../../common/logger';

@Injectable()
export class OutCallManager extends AbstractManager implements IOutCallManager {
  readonly className = 'OutCallManager';
  readonly logger = new ManagerLogger(this.className);

  @Inject()
  private readonly communicationManagerService: CommunicationManagerService;

  constructor(private context: ContextManagerService, private coreManagerService: CoreManagerService) {
    super(ServiceName.OutCall);
  }

  sendEmail(param: SendEmailInput): Observable<MessageHistoriqueContact> {
    const designation$ = param.clientId
      ? this.getClientDesignation(param.clientId, param.clientDesignation)
      : of(undefined);
    const communication$ = this.communicationManagerService.envoyerMail({
      to: param.emailAdress
    });
    return forkJoin([designation$, communication$]).pipe(
      switchMap(([designation, _com]) => {
        const historyEntry: MessageHistoriqueContact = {...};
        return this.historiqueContactService.postMessage(historyEntry);
      }),
      catchError((error) => this.throwError(error, 'sendEmail'))
    );
  }
}

this is my test class :

import {Test} from '@nestjs/testing';
import {OutCallManager} from './out-call.manager';
import { CommunicationManagerService } from 'package/communication-manager';

describe('OutCallManagerService', () => {
  let service: OutCallManager;
  const communicationManagerServiceMock = {};
  const coreManagerServiceMock = {};

  beforeEach(async () => {
    const moduleRef = await Test.createTestingModule({
      providers: [
        OutCallManager,
        
        {
          provide: CommunicationManagerService,
          useValue: communicationManagerServiceMock,
        },
        {
          provide: CoreManagerService,
          useValue: coreManagerServiceMock,
        },
      ]
    }).compile();
    service = moduleRef.get<OutCallManager>(OutCallManager);
  });

  describe('sendEmail', () => {
    it('should send email ', () => {
      const spyOnGetService = jest
        .spyOn(service, 'getService')
        .mockReturnValueOnce(histoContact)
        .mockReturnValueOnce(contacterSocle);
      const spyOnPostMessage = jest.spyOn(histoContact, 'postMessage').mockImplementation(() => of());
      const spyOnEnvoyerMail = jest.spyOn(contacterSocle, 'envoyerMail');
      const spyOnGetClientDesignation = jest.spyOn(service, 'getClientDesignation').mockReturnValue(of('designation'));
      const param: SendEmailInput = {
        emailAdress: '',
        clientId: '111111'
      };
      service.sendEmail(param).subscribe(() => {
        expect(spyOnGetService).toHaveBeenCalledTimes(2);
        expect(spyOnGetService).toHaveBeenCalledWith(SocfonMysysServiceName.HistoriqueContact);
        expect(spyOnGetService).toHaveBeenCalledWith(ServiceNameSocle.Communication);
        expect(spyOnPostMessage).toBeCalledTimes(1);
      });
    });}

the error is TypeError: Test suite failed to run

TypeError: coreManager.MessageSubject is not a function
 33 |   IParamCreerEMailBandeauWOX
  34 | } from package/communication-common';
> 35 | import {CommunicationManagerService} from 'package/communication-manager';
     | ^
  36 | import {ContextManagerService, CoreManagerService} from 'package/core-manager';

i tried to mock coreManager.MessageSubject but it is not the solution