Yokai

Yokai is an alternative test runner for ExUnit base on file watcher. Watchs for code changes and changes in the selected test files to auto trigger a new testa run hot reloading the code avoiding a cold start of the app/vm. The BEAM way.

Installation

# You need this to mix watch apply MIX_ENV=test for you.
def cli do
  [
    preferred_envs: [{:watch, :test}]
  ]
end

def deps do
  [
    {:yokai, "~> 0.3.1"}
  ]
end

Usage

# Run all tests and watch for changes
mix watch

# Run only this test file and watch for changes
mix watch test/module_name.exs

# Run all tests following a wildcard pattern
mix watch test/domain/*

# Increate the compile timeout for big projects.
mix watch --compile-timeout 60

While running, all changes to any file at lib/ or test/ will trigger a run.

But while it waits for a file change, you can enter commands yourself.

Menu

Command	Description
a	Run all tests once
q	Quit
r	Rerun tests
w	Update the test files pattern

Reason

The point is to have a faster iteration for then developing test/changes or applying TDD.

When talking about this idea it always come up that you need to reload the environment when you change a config. And to this there is 2 points against.

• Most of the time you are not changing configuration between runs, but when you do: mix test still there, exactly the same.
• The hot reload from Phoenix is good enough for most apps and workflows. This applies the same rules but for tests.

Goals

Have a fast code reloader and a nice CLI to quick iterate on development.

• Hot reload project code before each run
• Hot reload test file before each run
• Accept test file patterns to select test e.g accept test/*/sample*
• Option to clear console between run
• Keypress to trigger a run(Partially implemented, requires enter)
• Keypress to run all tests(Partially implemented, requires enter)
• Keypress to redefine the pattern(Partially implemented, requires enter)
• MCP server/tool for client to collect latest test run results.
• MCP tool to redefine runned configuration