Best way to unit your ExpressJS middleware

I am new to the NodeJS and seeking some advice on what would be the best approach on how to unit test a method in my controller.

Here's the method of my controller I want to test:

getAll: function(req, res, next) {
let pageNum = parseInt(req.query.pageNum, 10) || 0,
    pageSize = parseInt(req.query.pageSize, 10) || 500,
    orderBy = req.query.orderBy && req.query.orderBy.split(",");

return Tenant
        .query()
        .orderByAll(orderBy)
        .page(pageNum, pageSize)
        .then(results => {
            res.json(Object.assign(results, { pageNum, pageSize }));
        })
        .catch(next);

}

And here's my current test I wrote but is not working:

describe('Test getting all tenants without getting error', () => {
    it('body in res object should not be empty, and http status should be 200', () => {

        tracker.on('query', function checkResult(query) {
            query.response([{
                 "id": "6790ac7c-24ac-4f98-8464-42f6d98a53ae",
                 "name": "astar",
                 "publicKey": "this is a test"
            },
            {
                 "id": "7790ac7c-24ac-4f98-8464-42f6d98a53ae",
                 "name": "bstar",
                 "publicKey": "this is a test"
            }]);
        });

        tenantController.getAll(req, res, next).then(function() {
            console.log('Hello');
            expect(res.statusCode).to.equal(400);
            expect(JSON.parse(res._getData()).id).to.equal("shaflh;sahfl;s");
        }).catch(e => {
            console.log(e);
        })
    });
});

As you can see the method getAll returns a promise. I'm using knex and objectionjs for modelling and querying database (Postgresql). In my test i try to mock what I expect knex to return (using mock-knex), which is:

query.response([{
                 "id": "6790ac7c-24ac-4f98-8464-42f6d98a53ae",
                 "name": "astar",
                 "publicKey": "this is a test"
            },
            {
                 "id": "7790ac7c-24ac-4f98-8464-42f6d98a53ae",
                 "name": "bstar",
                 "publicKey": "this is a test"
            }]);

And it's not working, because I purposely put in code to print some thing out to the console and it doesn't print anything out at this moment:

tenantController.getAll(req, res, next).then(function() {
            console.log('Hello');
            expect(res.statusCode).to.equal(400);
            expect(JSON.parse(res._getData()).id).to.equal("shaflh;sahfl;s");
        })

At this point I would expect my promise would get rejected, but then nothing happens too in my catch:

catch(e => {
            console.log(e);
        })

My questions now would be: 1) In general, what would be a right thing to test for this getAll function. Right now, I'm testing if res object is updated with correct data, but not sure if it's a good way to test this function. 2) Is mocking a good approach in this situation? I'm trying to look for tutorials on mocking but it seems like testing with a real database is more popular in NodeJS world.