Elixir
Wallaby is an Elixir browser testing library that drives real browsers through WebDriver. Where Phoenix.LiveViewTest tests the server side without a browser, Wallaby tests the complete stack — JavaScript execution, CSS animations, WebSocket connections, and real browser rendering. It's the closest you get to testing what users actually
Elixir
Phoenix LiveView testing uses Phoenix.LiveViewTest to render LiveViews server-side and simulate user interactions without a browser. Tests run fast — no Selenium, no ChromeDriver — while still testing the full LiveView lifecycle: mount, events, component updates, and live navigation. This guide covers testing LiveViews and LiveComponents, simulating JS hook interactions, testing
Elixir
ExUnit is Elixir's built-in test framework. Most guides cover the basics — assert, refute, describe. But ExUnit has powerful features that separate good test suites from great ones: tags for selective execution, doctests that keep documentation accurate, async execution for faster runs, and custom assertions that make failures meaningful.
Elixir
Excoveralls generates test coverage reports for Elixir projects. It integrates with Coveralls.io for PR coverage comments, generates HTML reports for local review, and produces LCOV format for other coverage tools. Setting up coverage reporting early helps maintain quality as your Phoenix application grows. Installation # mix.exs def project do
Elixir
When Elixir applications call external HTTP services — payment processors, webhooks, third-party APIs — tests need to control those HTTP interactions. Bypass spins up a real HTTP server locally, intercepts requests your application makes, and lets you define exactly what responses to return. Unlike request-level stubs, Bypass tests your HTTP client configuration,
Testing
Phoenix.LiveViewTest and Phoenix.ConnTest test your application logic without a browser. For acceptance tests that verify the full user experience — JavaScript behavior, CSS-driven interactions, and visual rendering — you need real browser automation. Wallaby provides this for Elixir, integrating tightly with ExUnit and supporting concurrent test execution. What Wallaby Does
Testing
Phoenix applications expose their behavior through HTTP endpoints. Testing these endpoints — verifying correct status codes, response bodies, redirects, and authentication — is essential for confident Phoenix development. Phoenix.ConnTest provides exactly this capability, letting you exercise your controllers without starting an actual HTTP server. What Phoenix.ConnTest Does Phoenix.ConnTest builds
Testing
Phoenix LiveView enables rich, real-time web interfaces without writing JavaScript. Testing LiveView requires a different approach than traditional controller tests because LiveView components are stateful, event-driven, and update asynchronously. The Phoenix.LiveViewTest module provides the tools to test these interactions deterministically. How LiveView Testing Works Phoenix.LiveViewTest mounts a LiveView
Testing
Unit tests check specific examples: "given input X, the output is Y." Property-based testing asks a different question: "for ALL inputs with this shape, does this property always hold?" StreamData brings this paradigm to Elixir, integrating with ExUnit to automatically generate hundreds of test cases from
Testing
Elixir ships with a built-in testing framework called ExUnit. Unlike many languages where testing frameworks are third-party add-ons, ExUnit is part of the Elixir standard library and is the default choice for testing Elixir applications. This guide covers everything you need to write effective tests from day one. Setting Up
Testing
Testing code that calls external services — payment processors, email providers, third-party APIs — presents a challenge. You don't want real network calls in your test suite, but you also don't want to lose confidence in how your code handles those interactions. Mox, Elixir's standard mocking