How does Chai-HTTP integrate with Sinon in this situation?

[Minh Lu]

Here is the route I want to test:

```

app.post('/api/user', (req, res) => {

        dbService.replaceUserOnDuplicate(req.body, function returnResponse(insertedId) {

            if (insertedId === 0 || insertedId === req.body.id) {

                return res.sendStatus(200);                            

            }

            // TODO_MINH: Send an appropriate error to handle by the front-end

            return res.send({});

        });

    });

```

I can use chai-http to do something like this (psuedo-code):

```

it('test', function (done) {

            chai.request(server)

                .post('/api/user')

                .send({ user: SomeUserObject })

                .end(function (err, res) {

                    res.should.have.status(200);

                    done();

                });

        });

```

However, the api/users route makes a Database call. How would I use sinon to stub this method (replaceUserOnDuplicate) so that it returns a dummy response (like 0, or anything)?

Is it possible? I'm looking at the Chai-HTTP syntax and I see no room to insert any Sinon stubbed methods.

Thanks for your help!