Node Roundup: Mocha, Banzai, Inotify
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Mocha
Mocha (GitHub: visionmedia / mocha, License: MIT, npm: mocha) by TJ Holowaychuk is a new test framework that works both in Node and browsers. It runs tests serially, making it intuitive, and includes a huge collection of reporters including a TAP reporter. It even comes with a sane setup/teardown implementation, allowing code to be run before and after each test or the whole suite.
Like other test frameworks, Mocha uses an asynchronous “done” function. However, calling it is optional for synchronous code, and it can even accept an error to improve test reporting:
describe('User', function(){
describe('#save()', function(){
it('should save without error', function(done){
var user = new User('Luna');
user.save(function(err){
done(err);
})
})
})
})
TJ’s example shows that for methods that include an error as the first argument, then this will be automatically passed to done:
describe('User', function(){
describe('#save()', function(){
it('should save without error', function(done){
var user = new User('Luna');
user.save(done);
})
})
})
Mocha can work with any assertion library, which allows alternative assertion libraries like should.js to be used. It’s even possible to use BDD style tests describe() / it() or TDD: suite() / test().
TJ considers Mocha to be Expresso successor, and it does seem to address a lot of things that were missing from Expresso.
Banzai
Banzai (npm: banzai) by Pedro Teixeira is a document processing framework (or an ETL) that uses the concept of pipelines to represent state and perform multiple operations on a document. On the surface, a pipeline looks like a combination of an event-based API and a state machine:
pipeline
.on('initial', initialHandler, {
next: 'order received email sent'
})
.on('order received email sent', orderEmailSentHandler, {
priority: 2
, condition: allItemsAvailable
, next: 'items available'
})
.on('order received email sent', confirmationEmailSentHandler, {
priority: 1
, next: 'items not available'
})
.on('items not available', itemsNotAvailableHandler)
.on('items available', itemsAvailableHandler, {
next: 'order placed'
})
.on('order placed', orderPlacedHandler, {
next: 'order placed email sent'
});
Each pipeline is backed by a document store, and this is designed to be extensible. The first document store to be implemented is banzai-couchdb-store, but document stores only require a minimum of two functions to work with Banzai (load(docId, callback) and save(doc, callback)) so shouldn’t be too difficult to write support for more databases.
Pedro’s documentation includes a lot more details on pipelines, state handling, state stores, and work queues. Banzai seems like a useful tool for working with format conversion, but Pedro also notes it’s been used with Amazon Mechanical Turk.
Node Inotify
Node Inotify (License: MIT, npm: inotify) by Camilo Aguilar is an inotify API for Node and Linux. This library has been kicking around for over a year now, but the author and several contributors have been actively working on it.
The README includes a detailed code example, but the API is fairly straightforward: by using an instance of Inotify, addWatch() can be used to watch files or directories for changes. The callback fired when the file system changes receives an event which includes a mask that details what kind of change occurred.
