Why the world needs PhoenixTest

ElixirConf · February 10, 2025, 2:00pm

ElixirConf US 2024 - German Velasco

Welcome to ElixirConf

PhoenixTest is the missing library in the Elixir/Phoenix ecosystem.

Think about it, we have well established libraries for other core web-app needs:

Need interactive pages? LiveView

Need a database mapper? Ecto

Need a testing framework? ExUnit

Need background job processing? Oban

Need data pipelines? Broadway

But how do we test Phoenix applications?

… LiveViews are tested with LiveViewTest

… controllers are (I guess) tested with controller tests?

…. dynamicallly rendered pages (dead views) are tested with… (nothing?)

Isn’t that shocking?!

Phoenix is an amazing framework! But we don’t have a coherent, unified story around testing (like we do with ExUnit for Elixir).

We could use Wallaby or Hound (I have in the past). But that comes with another set of downsides:

Tests s-l-o-w d-o-w-n because everything is running through Chromedriver (an actual browser clicking buttons and stuff)

We have intermittent test failures (since we’re now dealing with a browser and potentially async operations)

We have Chromedriver failures! (Have you gotten that “invalid session id” error yet?)

You now have two different ways of testing LiveViews and dead views (and what happens when you want to test interactions between the two?).

That’s why I created PhoenixTest!

Join me as I walk you through why the world* needs Phoenix test.

We’ll talk about:

where it fits in the ecosystem,

why I think you should use it, and

… I’ll roll up my sleeves and live code () to show you how awesome it can be to test drive a Phoenix app!

You’ll come out equipped and ready to add PhoenixTest to your app for all your testing needs.

Comments welcome! View the elixirconf tag for more ElixirConf talks!