How to call external function in jest - node.js

Question

I'm New to unit test and trying to test my controller method.my project architecture design is as follow
Controller->Service->Model.
My test scenarios :
Pass correct parameters to controller method and test success response
Pass Invalid parameters to controller method and test error response
When i going to test scenario 1 ,according to my understanding i want to mock my programService and it return values.I have write test as follow and got errors.
I would really appreciate some one can fix this
ProgramsController.js
const ProgramService = require('../../services/program/programService');
class ProgramsController {
constructor() {
this.programService = new ProgramService();
}
async subscribe(req, res) {
try {
const { userId, uuid, msisdn, body: { programId } } = req;
const data = { userId, programId, msisdn, uuid }
const subscribe = await this.programService.subscribeUser(data);
res.json({
status: true,
message: 'Success',
friendly_message: constant.MSG.SUBSCRIPTION,
data: subscribe
})
} catch (error) {
res.status(500)
.json({
status: false,
message: 'Fail',
friendly_message: constant.MSG.SUBSCRIPTION_FAIL
})
}
}
}
ProgramService.js
class ProgramService {
constructor() {
this.subscriber = new Subscriber();
this.subsciberProgram = new SubsciberProgram()
}
async subscribeUser(data) {
try {
const { msisdn, userId, programId, uuid } = data;
...
return subscribedData;
} catch (error) {
throw error;
}
}
}
module.exports = ProgramService;
test.spec.js
const ProgramsService = require('../src/services/program/programService')
const ProgramsController = require('../src/controllers/programs/programsController')
const programController = new ProgramsController()
const programsService = new ProgramsService()
beforeAll(() => {
db.sequelize.sync({ force: true }).then(() => { });
});
const mockRequest = (userId, uuid, msisdn, body) => ({
userId,
uuid,
msisdn,
body,
});
const mockResponse = () => {
const res = {};
res.status = jest.fn().mockReturnValue(res);
res.json = jest.fn().mockReturnValue(res);
return res;
};
const serviceRecord = { userId: 1, programId: 1, msisdn: '56768382967', uuid: '46651a19-3ef1-4149-818e-9bd8a5f359ef' };
const fakeServiceReturn = { program_id: 1, amount: 5, no_of_questions: 10 }
describe('Subscribe', () => {
test('should return 200', async () => {
const req = mockRequest(
1,
'56768382967',
'46651a19-3ef1-4149-818e-9bd8a5f359ef',
{ 'programId': 1 }
);
const res = mockResponse();
const spy = jest.spyOn(programsService, 'subscribeUser').mockImplementation(() => serviceRecord);
await programController.subscribe(req, res);
expect(programsService.subscribeUser()).toHaveBeenCalledWith(fakeServiceReturn);
expect(res.status).toHaveBeenCalledWith(500);
expect(res.json).toHaveBeenCalledWith({
status: true,
message: 'Success',
friendly_message: 'successfull get data',
data : { program_id: 1, amount: 5, no_of_questions: 10 }
});
spy.mockRestore();
});
});
how can i mock programService.subscribeUser and test success response?

Answer 1

This mock should return a promise:
jest.spyOn(programsService, 'subscribeUser').mockImplementation(() => Promise.resolve(serviceRecord));