Testing authenticated / unauthenticated download links with Nightwatch.js - node.js

Question

I know there is a very similar question here: Testing download links with Nightwatch.js, but this case is slighly different.
I'm trying to test a download using nightwatch too, but it's not that simple due to the browser behavious which present a popup window to the user.
What i'm trying to do is to just download the file with node, and not using selenium (as in this python version: https://stackoverflow.com/a/24998532/447074)
So I made this custom assertion :
downloadFile.js :
var util = require('util');
var http = require('http');
var url = require('url');
exports.assertion = function(options, expected_status, msg) {
this.message = msg || util.format('Testing if authenticated file download works');
this.file_url = options.file_url;
this.cookie_content = options.cookie_content;
this.expected = expected_status;
this.pass = function(value) {
return this.expected == value
};
this.value = function(response) {
return response.statusCode;
};
this.command = function(callback) {
var options = url.parse(this.file_url);
options.headers = {
'Cookie': this.cookie_content
};
http.get(options, callback);
return true;
};
};
And using it in a test case like this:
// I would not use this here, but I added this for this post...
"Get cookie": function(browser) {
var settings = browser.globals;
var state = browser.globals.state;
browser
.getCookies(function(response) {
state.sessionid = "sessionid=" + response['value'].filter(function(cookie_value){
return cookie_value['name'] == 'sessionid';
})[0]['value'];
})
},
"An authenticated user can download the file": function(browser) {
var settings = browser.globals;
var state = browser.globals.state;
browser
.assert.downloadFile({file_url: "http://example.com/somefile.pdf", cookie_content: state.sessionid}, 200, "Testing Authenticated download");
},
"An unauthenticated user can not download the file": function(browser) {
var settings = browser.globals;
var state = browser.globals.state;
browser
.assert.downloadFile({file_url: "http://example.com/somefile.pdf", cookie_content: "sessionid= wrong-session;"}, 302, "Testing Unauthenticated dowload");
},
It's "almost" working, but somehow the test "stops" after the first test, just after the first downloadFile assertion.
Here is the result from the console
nightwatch -c ./nightwatch.json --test tests/documents/upload_test.js
[Upload Test] Test Suite
========================
Setting up...
Running: Get cookie
No assertions ran.
Running: An authenticated user can download the file
✔ Testing Authenticated dowload
Is it ok to make this kind of assertion in nightwatch?
Why does it stops the tests?
Thanks!

Answer 1

Ok I found the solution by reading the custom assertion doc again: http://nightwatchjs.org/guide#custom-assertions
The command function of the assertion needs to return this http://nightwatchjs.org/guide#custom-assertions.
Here is the downloadFile.js assertion :
var util = require('util');
var http = require('http');
var url = require('url');
exports.assertion = function(options, expected_status, msg) {
this.message = msg || util.format('Testing if authenticated file download works');
this.file_url = options.file_url;
this.cookie_content = options.cookie_content;
this.expected = expected_status;
this.pass = function(value) {
return this.expected == value
};
this.value = function(response) {
return response.statusCode;
};
this.command = function(callback) {
var options = url.parse(this.file_url);
options.headers = {
'Cookie': this.cookie_content
};
http.get(options, callback);
return this;
};
};