Jest mock twilio - how to? - unit-testing

Question

I have been using Jest to do my unit tests with node.
I am used to mocking the first level of the modules/functions, but on the challenge to mock Twilio, I am not having so much luck.
I am using the twilio method: client.messages.create, so here I have the twilio client from the constructor require('twilio')(account sid, token), and the first layer is from the object/method(?) messages, and last the third level create, and it's this last guy that I am trying to mock.
I was trying something like this:
jest.mock('twilio', () => {
const mKnex = {
messages: jest.fn(),
};
return jest.fn(mKnex);
});
However, I am not able to mock the client resolved value, where I get client.message.create is not a function.
If I try the above mock plus this client.messages.create.mockReturnValueOnce({sid: "FOO", status: "foo"); I get that cannot read the property create from undefined(messages).
Any tip, post, docs that could give me some luck on this?
Thanks

Answer 1

The solution for this is:
Create a file for Twilio client:
// sms.client.ts
import { Twilio } from 'twilio';
const smsClient = new Twilio(
'TWILIO-ACCOUNT-SID',
'TWILIO-TOKEN'
);
export { smsClient };
Then, your service file should look like this:
// sms.service.ts
import { smsClient } from './sms.client';
class SMSService {
async sendMessage(phoneNumber: string, message: string): Promise<string> {
const result = await smsClient.messages.create({
from: '[phone]',
to: phoneNumber,
body: message,
});
if (result.status === 'failed') {
throw new Error(`Failed to send sms message. Error Code: ${result.errorCode} / Error Message: ${result.errorMessage}`);
}
return result.sid;
}
}
export const smsService = new SMSService();
Last but not least, your spec/test file needs to mock the client file. E.g.
// sms.service.spec.ts
import { MessageInstance, MessageListInstance } from 'twilio/lib/rest/api/v2010/account/message';
import { smsClient } from './sms.client';
import { smsService } from './sms.service';
// mock the client file
jest.mock('./sms.client');
// fixture
const smsMessageResultMock: Partial<MessageInstance> = {
status: 'sent',
sid: 'AC-lorem-ipsum',
errorCode: undefined,
errorMessage: undefined,
};
describe('SMS Service', () => {
beforeEach(() => {
// stubs
const message: Partial<MessageListInstance> = {
create: jest.fn().mockResolvedValue({ ...smsMessageResultMock })
};
smsClient['messages'] = message as MessageListInstance;
});
it('Should throw error if response message fails', async () => {
// stubs
const smsMessageMock = {
...smsMessageResultMock,
status: 'failed',
errorCode: 123,
errorMessage: 'lorem-ipsum'
};
smsClient.messages.create = jest.fn().mockResolvedValue({ ...smsMessageMock });
await expect(
smsService.sendMessage('[phone]', 'lorem-ipsum')
).rejects.toThrowError(`Failed to send sms message. Error Code: ${smsMessageMock.errorCode} / Error Message: ${smsMessageMock.errorMessage}`);
});
describe('Send Message', () => {
it('Should succeed when posting the message', async () => {
const resultPromise = smsService.sendMessage('[phone]', 'lorem-ipsum');
await expect(resultPromise).resolves.not.toThrowError(Error);
expect(await resultPromise).toEqual(smsMessageResultMock.sid);
});
});
});

Answer 2

I've found a solution. It's still calling the endpoint, but for each twilio account, you get a test SID and Token, I used this one so it does not send a sms when testing with this:
if (process.env.NODE_ENV !== 'test') {
client = require('twilio')(accountSid, authToken)
listener = app.listen(3010, function(){
console.log('Ready on port %d', listener.address().port)
})
}else{
client = require('twilio')(testSid, testToken)
}