express node.js testing wallaby.js

Avoiding EADDRINUSE when using wallaby.js with an express project

I’ve had great luck using wallaby.js on client side JavaScript and I’d like to try to get it to work on my server side JavaScript. However, wallaby.js likes to spin up a lot of parallel web servers which causes problems for the tests because it keeps on throwing EADDRINUSE errors.

The basic scaffolding of my project was done with the Yeoman angular-fullstack generator, so my server code sits in /server and most of the methods are in /server/api.

Thus far, I’ve managed to get it to kinda work with the following configuration:

module.exports = function () {
return {
files: [
{ pattern: 'server/**/*.spec.js', ignore: true }
tests: [
env: {
type: 'node',
debug: true,
workers: {
initial: 1,
regular: 1,
recycle: false

Here you can see that I’m setting the number of wallaby workers to 1 and not allowing it to recycle workers. It works fine the first time through, but after I start to edit files I get occasional EADDRINUSE errors.

Is there a preferred mechanism for using wallaby.js with express and avoiding it from spawning multiple test server processes all on the same port, thereby eliminating the EADDRINUSE errors?