Mocking S3 in Node.js using Sinon

index.js

var Aws = require('aws-sdk');
var sinon = require('sinon');

// Only works for 'createBucket', 'update' and a few others since most API methods are generated dynamically
// upon instantiation. Very counterintuitive, thanks Amazon!
var createBucket = sinon.stub(Aws.S3.prototype, 'createBucket');
createBucket.yields(null, 'Me create bucket');

// For other methods, we can 'assign' the stubs to the proto, already defined function won't be overridden
var listBuckets = Aws.S3.prototype.listBuckets = sinon.stub();
listBuckets.yields(null, 'Me list buckets');

var s3 = new Aws.S3();
s3.createBucket({Bucket: 'my-bucket'}, function(err, arg1) {
    console.log(arg1);
});
s3.listBuckets(function(err, arg1) {
    console.log(arg1);
});

console.log('Called #createBucket() ' + s3.createBucket.callCount + ' time(s)');
console.log('Called #listBuckets() ' + s3.listBuckets.callCount + ' time(s)');

package.json

{
  "name": "node-s3-stub",
  "version": "0.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "BSD",
  "dependencies": {
    "sinon": "~1.14.1",
    "aws-sdk": "~2.1.17"
  }
}