HTTP Harness for Node.js API Development

Copyright (C) 2016-2017 David Betz

Purpose

Put simply: to aid in building Node.js HTTP APIs

Testing HTTP tests too much and creating a fake endpoint doesn't actually help you develop your endpoint. Just build the req and res and be done with it.

Usage

Writing your tests

test/samples.js (adapted for external use)

You need httpHarness. I use idgen to generate fake IDs:

const httpHarness = require('http-harness')
const idgen = httpHarness.idgen

Review the following test sample, then review following commentary:

const createRequestOptions = () => {
    return Object.assign({}, {
        user: {
        },
        url: 'https://domain.local/api/samples'
    })
}

it("add new sample", function (done) {
    const user_id = idgen.generate(this.test.title)

    const ro = createRequestOptions()
    ro.user._id = user_id
    ro.body = { value: 12345 }

    const req = httpHarness.createRequest(ro)
    const res = httpHarness.createResponse()

    res.setDone((obj) => {
        expect(obj.code).to.equal(200)
        expect(obj.json_obj.length).to.gt(10)
        done()
    })
    samples.post(req, res, () => { })
})

Now for the commentary...

For the sake of this test, I'm generating a unique ID as a user_id (do whatever you want):

const user_id = idgen.generate(this.test.title)

This uses the title of the test as the randomization seed.

Then I create an HTTP request object and add stuff to it. In this case, I'm adding user._id because that's what my passport-based API uses internally for authentication. createRequestOptions simple provides a template; use it to add whatever you want to the request.

const ro = createRequestOptions()
ro.user._id = user_id
ro.body = { value: 12345 }

Then I create the req/res objects. This is the same every time.

const req = httpHarness.createRequest(ro)
const res = httpHarness.createResponse()

Then I set my callback (dump the output of obj to screen to see what you're dealing with; output isn't always json_obj):

res.setDone((obj) => {
    expect(obj.code).to.equal(200)
    expect(obj.json_obj.length).to.gt(10)
    done()
})

Finally, I call the API:

samples.post(req, res, () => { })

Making your APIs testable

In the previous usage section, samples.post is called. That needs to exist and be callable.

To make this happen, you simply decouple your export from express:

endpoints/samples.js (partial snippet)

module.exports.post = function (req, res, next) {
    debug("POST /api/samples")
    if (typeof req.user === 'undefined' || typeof req.user._id === 'undefined') {
        return response.send401(res)
    }
    const user_id = req.user._id
    const session_id = idgen.generate('sample::post')
    const item = Object.assign({}, req.body)
    memorydb.insert(user_id, session_id, item)
        .then(p => response.sendJson(res, 200, p))
        .catch(err => response.routeError(res, err))
}

module.exports.init = function (app) {
    app.post("/api/samples", auth0.authCheck, module.exports.postSample)
}

This follows the pattern of calling init from your index to initialize your endpoint. You don't have to do that; it simply allows you to keep express decoupled from the API logic itself.

Tips

Copy by-value when sending stuff to your test. JavaScript's by-ref default often causes unexpected results. For example, if you're modifying your body input in your API, this would be modified in your tests too. That's just how by-ref works. The following is a by-value copy in JavaScript:

const item = Object.assign({}, req.body)

This creates a new object ({}), copies req.body to it, then returns.

The same goes for arrays. If you don't want to pass around a reference to your array, create a copy:

const myNewArray = myArray.slice(0)