Front End Testing using Elixir


My current company’s ecommerce website is on Drupal 7. I am trying to find a way (excuse) to use Elixir more in my workplace. In order to achieve this, I was thinking of creating a front end testing tool using Elixir.

My Question:

  1. Has anyone here created a front end testing tool using Elixir which tests a website on a re-occuring bases?
  2. Is this a good idea? Should I abandon Elixir for front end testing and stick to something like cypress?

Maybe relevant:

I must try this kind of thing out sometime. :slightly_smiling_face:

This looks interesting.

There is Wallaby also… both Hound and Wallaby work well for automated E2E browser testing.

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Hound works very well for this. I am currently deploying hound against a django bff that runs in front of a django backend and it was incredibly effective at demonstrating that the elixir replacement backend that I wrote is an effective substitute that doesn’t die after long term burn in testing.

I can’t compare it to anything else (it’s been ages since I used capybara) but I wrote a repeating test and having it be a supervised process in elixir meant I didn’t have to nail down all corner cases (also my tests called out other services like ssh to confirm side effects), if it crashed the tests would restart from a safe state

I tried wallaby, but there were simply a few things that couldn’t trigger as reliably as hound does, so I stuck with hound, even though it’s imperative syntax is less to my liking. I got used to it though.


Thanks @tme_317 and @ityonemo for your insight. I’m going to take a look at both wallaby and hound. Ideally I would like go with the library that sees to build out.

We tried both out and ended up going with Wallaby. The experimental chrome driver has been working out great for us!


I’m bring this post back to life to ask the following question. Is it possible to use Wallaby or Hound to test external sites, outside of ExUnit?

I want to build a Front End QA tooling that has a set of endpoints for me to utilize from another website. Essentially I want to utilize the QA tool from website A to test website A. I understand this seem unnecessary, but I feel that this would be a good way for me to introduce Elixir to your company without impacting business logic.

Yes, 100%. At work I replaced a python backend with elixir (I’m coming for the python frontend next) and tested that it worked by running a user story continuously using hound for one week in our staging/lab environment (against the python frontend). Discovered several errors, and since deploying to prod there have been zero backend errors.

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As a protip, if you do this, BEAM supervised restarts are key and I found that I needed to System.cmd(“killall”, [“chromedriver”]) on each restart, because I found that chromedriver could become helplessly lost in the face of our high-latency python frontend that doesn’t handle conflicting state very well, but that’s another story altogether.

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That’s awesome! Any chance @ityonemo you can provide me a resource you used to build the tester, or do you have an open source version of the tester?

I’m trying to understand how to run hound or wallaby outside of testing :confused:

sadly I don’t have an open source version of the tester. I did kind of write a testing framework, but it’s not really ready to be open sourced anytime soon. It’s also somewhat tightly integrated into a set of releases, that’s probably more than you would need.

In your case I would recommand making a custom mix task.

oh you will very much want to do this at the head of your mix task or else you’ll be wondering why nothing works:

# linux, very hacky, MacOS - ymmv
  @spec ensure_running(non_neg_integer) :: :ok
  def ensure_running(sleep_time \\ 500) do
    {ps, _} = System.cmd("ps", ["aux"])
    unless ps =~ "chromedriver" do
      chromedriver_executable = System.find_executable("chromedriver")

      {:ok, _pid} = Task.start(fn ->
        System.cmd(chromedriver_executable, [], stderr_to_stdout: true)

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Gotcha! This is what I was looking for. I’ll update this post when I have built a generic testing framework.

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Have you gotten anywhere with this? I’ve found myself in exactly your situation and would love to know if you figured out a great way to do it!