Replace the value of a variable when testing a function

Question

I have a route that records user data and gives a unique identifier.

router.post('/', (req, res) => {
    const user_email = req.body.user_email;
    const username = req.body.username;
    const user_phone = req.body.user_phone;
    const service_sid = serviceSidVerification(user_phone);
    const entry_id = uuidv4();
    const user = new User(
        username,
        user_email,
        user_password,
        user_phone,
        entry_id,
        service_sid,
    );
    await db.query(user.setUser());
    return res.status(200).json({
        entry_id: entry_id,
    });
});

I want to write a test for this route. I need to replace the return value from the serviceSidVerification() function with my own. For example, 12345. How can this be done with a test?

This is what my test looks like.

describe(`Users Test`, () => {
    describe('POST /api/users/', () => {
        it(`Should create user`, (done) => {
            let stub = sinon.createStubInstance(server);
            stub.getEvents.returns('12345')
            chai
                .request(server)
                .post('/api/users/')
                .send({ 'username': faker.internet.userName() })
                .send({ 'user_email': faker.internet.email() })
                .send({ 'user_password': faker.internet.password() })
                .send({ 'user_phone': faker.phone.phoneNumber() })
                .end((err, res) => {
                    expect(res).have.status(200);
                    expect(res.body).have.property('entry_id');
                    expect(res.body.entry_id).to.be.an('string');
                    done();
                });
            });
        });
    });
});

...

function ServiceSidVerification(phone) {
    const client = new twilio(config.smsVerify.accountSid, config.smsVerify.authToken);
    const service_sid = (await client.verify.services
        .create({
            friendlyName: config.smsVerify.title,
            codeLength: config.smsVerify.codeLength,
        })
    ).sid;
    const sid = (await client.verify.services(service_sid).verifications
        .create({
            to: phone,
            channel: 'sms'
        })
    ).sid;
    return { service_sid, sid };
}

How do I test my route?

Denny · Accepted Answer · 2019-08-12 10:13:03Z

1

To change the behavior of serviceSidVerification() you can use sinon. If you decide to go this way, you'll have to require sinon in the tests file + the module, where serviceSidVerification resides. Then, before executing the test you'll have to do something like this:

const stubServiceSidVerification = sinon.stub(yourModule, 'serviceSidVerification')
    .returns('yourValue');

Please note that if you use sinon, serviceSidVerification should be exported as the property of an object and not as a standalone function because of this issue.

Another option is to use proxyquire.

answered Aug 12, 2019 at 10:13

Denny

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6 Comments

MegaRoks Over a year ago

I get an error Cannot stub non-existent own property serviceSidVerification

Denny Over a year ago

Can you share the code where serviceSidVerification is defined and exported and the code where you try to stub it?

MegaRoks Over a year ago

Added. The function is in the same file.

Denny Over a year ago

What sinon can do is stub(replace) the specified function when a test calls the API that uses that function. In your case it could change the behavior of serviceSidVerification when the test hits the endpoint. In order to do that, that function must be required and stubbed where the test is executed. You've said that serviceSidVerification is defined in the 'same file' - what file do you mean? Also, I can't see where it gets stubbed. I see sinon.createStubInstance(server) but I'm not sure that this is what is needed in this case.

MegaRoks Over a year ago

I cannot figure out how to test this route. Is there an example or explanation?

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