I have been using the following coding style in tests for a while:
// Load in our dependencies
var expect = require('chai').expect;
var httpUtils = require('./utils/http');
var serverUtils = require('./utils/server');
// Define our tests
describe('A request to GET /', function () {
// Start our server, make our HTTP request, and save its info to `this`
serverUtils.run();
httpUtils.save(serverUtils.getUrl('/'));
// Perform our assertions
it('has no errors', function () {
expect(this.err).to.equal(null);
expect(this.res.statusCode).to.equal(200);
});
it('receives expected content', function () {
expect(this.body).to.contain('Hello World!');
});
});
Without utilities this would look like:
// Load in our dependencies
var expect = require('chai').expect;
var request = require('request');
var server = require('../server/index');
// Define our tests
describe('A request to GET /', function () {
// Start our server
// DEV: This is an over simplification of server setup/teardown
before(function serverUtilsRun () {
server.listen(8080);
});
before(function cleanupServerUtilsRun () {
server.close();
});
// Make our HTTP request and save its info to `this`
before(function httpUtilsSave (done) {
var that = this;
request('http://localhost:8080/', function handleRequest (err, res, body) {
that.err = err;
that.res = res;
that.body = body;
done();
});
});
after(function cleanupHttpUtilsSave () {
delete this.err;
delete this.res.statusCode;
delete this.body;
});
// Perform our assertions
it('has no errors', function () {
expect(this.err).to.equal(null);
expect(this.res.statusCode).to.equal(200);
});
it('receives expected content', function () {
expect(this.body).to.contain('Hello World!');
});
});
For those curious about how this works, Mocha has a this context which is shared by before, after, and it.
I prefer this coding style due to its compactness, reusability, and extensibility.
We can take this further by supporting chaining (e.g. here is how I test things like CSRF):
// Load in our dependencies
var expect = require('chai').expect;
var httpUtils = require('./utils/http');
var serverUtils = require('./utils/server');
// Define our tests
describe('A request to POST /', function () {
// Start our server
serverUtils.run();
describe('with a CSRF token', function () {
// Make our HTTP request
// DEV: `session.init()` will create a cookie jar
// DEV: `session.save()` will use said cookie jar
// DEV: See htmlForm and expectedStatusCode definitions here
// https://github.com/twolfson/twolfson.com/blob/3.102.0/test/utils/http.js#L15-L66
httpUtils.session.init()
.save(serverUtils.getUrl('/'))
.save({
method: 'POST',
url: serverUtils.getUrl('/')
htmlForm: true,
expectedStatusCode: 200
});
// Perform our assertions
it('is successful', function () {
// Asserted by `expectedStatusCode`
});
});
describe('without a CSRF token', function () {
// Make our HTTP request
httpUtils.session.init()
.save({
method: 'POST',
url: serverUtils.getUrl('/')
expectedStatusCode: 400
});
// Perform our assertions
it('is rejected', function () {
// Asserted by `expectedStatusCode`
});
});
});
Recently I've been exploring solutions to reduce repetition among tests (and even add required tests) by wrapping top level describes as another function (e.g. scenario):
// Performs serverUtils.run() and database fixture setup
scenario('A request to GET /', function () {
// Make our HTTP request
httpUtils.save({
url: serverUtils.getUrl('/'),
expectedStatusCode: 200
});
// Perform our assertions
it('is successful', function () {
// Asserted by `expectedStatusCode`
});
});
https://gist.github.com/twolfson/1ddf42a41bffefb8c2f298c082e4a337
https://gist.github.com/twolfson/6b2919b9b83dc54c270a9c89db973288
Lessons learned and further reading
I recommend against using utilities for it tests; it's implicit that the utilities are for before/after actions only. As a result, when we compare the CLI output to the code, it's hard to identify where the test is coming from.
Example: https://github.com/twolfson/spritesheet-templates/blob/7.2.0/test/css_test.js#L35-L40
I used to publish packages for these (request-mocha, mocha-fixture-dir). However, I have found that utilities change frequently enough that it's impractical to maintain. Instead I will typically copy/paste among repos. Here are some samples from my latest project: