angular.module('app')
  .service('someService', [
    '$http',
    '$q',
    function ($http, $q) {
      var url = 'http://www.whatever.com',
        fd = new FormData(),
        self = this;

      self.createFile =  function(file) {

        var deferred = $q.defer(),
          promiseResult;

          fd.append('files', file);
          $http.post(url, fd, { transformRequest: angular.identity,
            headers: {'Content-Type': undefined})
            .then(function(result) {
                deferred.resolve(result);
            }, function(error) {
              deferred.reject(error);
            });
        }
        promiseResult = deferred.promise;
        return $q.when(promiseResult);
      };

}]);


fakeFile = {name : 'icon.jpg', size: 1024, type: 'c', lastModified: new Date(0), content: 'abcde'};
someService.uploadFile(fakeFile, dest)

$httpBackend
.expectPOST(dest,
function(postData) {
   console.log(postData) //-> IS EMPTY :(
   return true;
})
.respond(200);