CI with Node.JS and MongoDB© Niall O’Higgins niallo@frozenridge.cohttps://github.com/FrozenRidge/node-mongodb-ci-webinar

Continuous Integration with Node

We define CI as “automatically running a test suite on each commit to a VCS and reporting success and failure”

● CI requires you to have a test suite● Node makes it easy to specify a test suite● NPM encourages you to have one

Create Node.JS Project w/ Tests

Live coding!

1. `npm init` in empty directory2. Hit return on prompts3. Run `npm test`4. What happens?

Testing in Node.JS

Our empty new project’s test suite failsLet’s write a test suite!

But first we should talk a little about writing tests in Node.JS

Testing in Node.JS

What is a test suite? A test suite consists of:

● Test Runner● Assertion Library● Tests

Node Test Runners

A Test Runner simply runs your test suite and reports results.

● Gives structure to your test suite● Could be just a shell or Node script● You can roll your own or use something off-

the-shelf

Node Test Runners

Some Popular Node.JS Test Runners:● Mocha● Nodeunit● Node-Tap● Vows

Node Test Runners

We like to use Mocha. It works in the browser and Node. It has many reporting formats.

You should feel free to choose whichever suits you best.

Node.JS Assertion Libraries

An Assertion Library is used to compose predicates which make up each test.

● `if` and `throw`● Node ‘assert’ module in stdlib● ChaiJS● ShouldJS

Assertion Styles: TDD vs BDD

Mostly matter of emphasis and preferenceBDD = more “English-like” assertionsexpect(myVar).to.equal(“hello”)

TDD = more “code-like” assertionsassert.equal(myVar, “hello”)

Assertion Style: TDD vs BDD

BDD:expect(myArray).to.have.length(3)

TDD:assert.equal(myArray.length, 3)

Assertion Style: TDD vs BDD

We use ChaiJS as our Assertion Module as it:

● supports both TDD and BDD styles. ● has many convenient assertions.

Create Node.JS Project w/Tests

Let’s return to our Node.JS project.We shall create a test suite with Mocha and Chai.

1. `npm install --save-dev mocha chai`2. Change tests (`sed -i -e 's/echo.*/\.\/node_modules\/\.bin\/mocha"/g' package.json`)

Create Node.JS Project w/Tests

Now if you run `npm test` mocha should start

There are no tests, so there are no errors.

Let’s create a test!

Create Node.JS Project w/Tests

But we haven’t said what we’re testing!

Let’s test a function that:

Returns whether the string ‘tdd’ exists in an argument.

Create Node.JS Project w/Tests

1. Create a file named `test/test_index.js`2. It should have the following contents:

var expect = require(‘chai’).expect

var isTdd = require(‘../index.js’).isTdd

describe(‘#index’, function() {

it(‘should return false if string tdd is not in argument’, function() {

var s = “just bdd here”

expect(isTdd(s)).to.be.false

})

})

Create Node.JS Project w/Tests

1. Run tests2. They fail!3. No implementation

Create Node.JS Project w/Tests

Add implementation in file “index.js”:

module.exports = { isTdd: function(s) { return s.indexOf('tdd') !== -1 }}

Finally tests pass!

Node.JS Project w/ MongoDB

That’s very silly, basic TDD / BDD in Node. Enough to get the idea.

Now let’s talk about MongoDB and do some coding!

[ Finished code at https://github.com/FrozenRidge/ci-node-mongodb-test ]

Node.JS & MongoDB User Store

We shall create a user object store interface.

Users can be retrieved by username or email.

To test this, we write an integration test whichtalks to MongoDB.

MongoDB Data Fixtures

We see there is a problem, in that to test correct behaviour we must load data (aka fixtures) into MongoDB.

We can do this in Mocha using “before” and “after” phases.

Make MongoDB URL Configurable

MongoDB URI should be configurable via environment variable - see 12factor.net

e.g. process.env.MONGODB_URL

Works great with CI servers like StriderCD, too!

Larger MongoDB Fixture Data Sets

In our example, we wrote our fixture data using the driver.

For larger data sets, you may want to use binary dumps/restores. You can run the `mongorestore` binary to load these.

MongoD Options for Faster CI

--nojournaling - You probably don’t need the safety for CI.--small - Use smaller default file sizes.--noprealloc - Don’t pre-allocate files. Useful if startup time with a fresh database is a bottleneck.

Thanks!

Feel free to get in touch - we’re here to help!

niallo@frozenridge.co / http://frozenridge.co@niallohiggins on Twitter

http://stridercd.com - Our Open Source CI server written in Node.JS and MongoDB