http://stackoverflow.com/q/38820196/3349511

app-test.js

var chai      = require('chai'),
    should    = chai.should(),
    expect    = chai.expect(),
    assert    = chai.assert,
    supertest = require('supertest-as-promised'),
    api       = supertest('http://localhost:3000');

describe('Pictures', function () {
    it('should add a picture', function (done) {
        api.post('/api/v1/pictures')
            .set('Accept', 'application/json')
            .attach('userPhoto', __dirname + '/import/user0.jpg')
            .expect(200)
            .then(function (response) {
                done();
            });
    });
});

app.js

var express        = require('express'),
    path           = require('path'),
    logger         = require('morgan'),
    bodyParser     = require('body-parser'),
    app            = express(),
    methodOverride = require('method-override'),
    multer         = require('multer'),
    upload         = multer({
      dest: 'uploads/',
      fileFilter: function(req,file,cb){
        cb(null,true);
      }
    }).single('userPhoto');

app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended:false}));
app.use(methodOverride('X-HTTP-Method'));          // Microsoft
app.use(methodOverride('X-HTTP-Method-Override')); // Google/GData
app.use(methodOverride('X-Method-Override'));

app.post('/api/v1/pictures', function(req, res) {
  upload(req, res, function(err) {
      if(err) {
          console.log(err);
          res.status(409).send('file not uploaded correctly');
      }
      else {
          res.end('File uploaded correctly');
      }
  });
});

app.listen(3000);

package.json

{
  "dependencies": {
    "body-parser": "^1.15.2",
    "chai": "^3.5.0",
    "express": "^4.14.0",
    "method-override": "^2.3.6",
    "mocha": "^3.0.2",
    "morgan": "^1.7.0",
    "multer": "^1.2.0",
    "supertest": "^2.0.0",
    "supertest-as-promised": "^3.2.0"
  }
}