Issue while (unit test) mocking container.get service

[lineldcosta]

Hello santiq,

I am back again:-)!. Hey i am having issues in unit testing container.get(service), checkout the below code.

import * as _ from 'lodash';
import {Service, Inject, Container} from 'typedi';
import OTPService from '../otp/index';

@Service()
export default class DevicechangeService {
  constructor(@Inject('devicechangeModel')private devicechangeModel, @Inject('otpModel')private otpModel, @Inject('logger')private logger,) {}

  /**
   *
   * Service to change the device
   *
   * @method deviceChange
   * @param {number} accountId
   * @param {string} deviceId
   * @param {number} mobile
   * @return {object} resolves after sending otp
   */

  public async deviceChange(accountId : number, deviceId : string, newdeviceId : string, created : number, mobile : number,) : Promise < any > {
    try {
      await this
        .devicechangeModel
        .addDeviceChangeDetails(accountId);

       let OTPServiceInstance = Container.get(OTPService);


      await this
        .otpModel
        .updateOTPtoInactiveForModule('DEVICE_CHANGE', accountId);
      //get the new otp

        //get the user details
        //send the otp
        let result = await OTPServiceInstance.sendOTP(serviceprovider, mobile, otpMessage, isd);
        if (result instanceof Object) {
          return result;
        }
        return true;
      } else {
        return {
          field: 421,
          message: errorCode('account').getMessage(421)
        };
      }
    } catch (e) {
      throw e;
    }
  }
}

Here i am not able to set mock class for OTPService, so not able to alter container.get(OTPService) from the above code.

I have tried below but still it does'nt come inside mocked service.

@Service()
class OTPService {
  public generateOTP : any = jest
    .fn()
    .mockImplementation(async(accountId : number, deviceId : string, status : string) => new Promise((resolve : any) => {
      console.log('calls here')
      resolve({})
    }),);
  public sendOTP : any = jest
    .fn()
    .mockImplementation(async(serviceprovider : string, mobile : number, otpMessage : string, isd : number) => new Promise((resolve : any) => resolve({})),);
}

describe('Account', () => {
  beforeEach(done => {
    Container.set(OTPService, new OTPService());
    done();
  });
  describe('#deviceChange', () => {
    it('check everyting cool', async done => {
      let logger = {};
      let otpModel = {
        updateOTPtoInactiveForModule: jest
          .fn()
          .mockImplementation(async(deviceChange : string, accountId : number) => new Promise((resolve : any) => resolve(true))),
        getUserPhoneService: jest
          .fn()
          .mockResolvedValue(true)
      };
      let devicechangeModel = {
        addDeviceChangeDetails: jest
          .fn()
          .mockResolvedValue(true),
        updateDeviceChangeToInactive: jest
          .fn()
          .mockResolvedValue(true)
      };
      // Container.set('OTPService', new OTPService());
      let DeviceChangeServiceInstance = new DeviceChangeService(devicechangeModel, otpModel, logger);
      let deviceChangeStatus = DeviceChangeServiceInstance.deviceChange(accountId, deviceId, newdeviceId, created, mobile);
    });
  });
});

Guys any idea how to solve this...

[santiq]

In the unit test code, you don't have to use Container nor the @service or @Inject decorators.

The idea is that you mock every dependency of the class that you are going to test.

Also, you don't necessarily need to write a Class for the mock, just use a normal object with the involved functions mocked with jest

describe('Account', () => {
  describe('#deviceChange', () => {
    it('check everyting cool', async done => {
      let logger = {};
      let otpModel = {
        updateOTPtoInactiveForModule: jest
          .fn()
          .mockImplementation(async(deviceChange : string, accountId : number) => new Promise((resolve : any) => resolve(true))),
        getUserPhoneService: jest
          .fn()
          .mockResolvedValue(true)
      };
      let devicechangeModel = {
        addDeviceChangeDetails: jest
          .fn()
          .mockResolvedValue(true),
        updateDeviceChangeToInactive: jest
          .fn()
          .mockResolvedValue(true)
      };
      let DeviceChangeServiceInstance = new DeviceChangeService(devicechangeModel, otpModel, logger);
      let deviceChangeStatus = DeviceChangeServiceInstance.deviceChange(accountId, deviceId, newdeviceId, created, mobile);
    });
  });
});

Now the problem that I see in your code is that you are using the service locator to obtain a dependency that should be injected into the constructor.

So, what I'm saying is that you need to change this

 let OTPServiceInstance = Container.get(OTPService);

For this

  constructor(
    @Inject('devicechangeModel')private devicechangeModel, 
    @Inject('otpModel')private otpModel,
    @Inject('logger')private logger,
    @Inject() private OTPServiceInstance: OTPService, // Here is injected.
) {
}

The function Container.get (formal name 'Service Locator') should only be used in the entry point of the code execution
In this project, that is at top-level code in the API Route Controller.
Also in the event handlers, because the execution is detached from the API controller context

What do you think?

[lineldcosta]

Hello santiq,

Sorry for the delay, but as per ur instructions, i implemented it and works perfectly, and checked out other git repo like many have implemented the same way you have guided.

Thanks satiq,