https://magnitude.run / ruby minitest integration

generator.rb

# lib/generators/magnitude_generator.rb
class MagnitudeGenerator < Rails::Generators::Base
  source_root File.expand_path('templates', __dir__)
  desc "Installs Magnitude.run integration with Minitest DSL, helper, and example test"

  def create_script_builder
    template "script_builder.rb", "lib/magnitude/script_builder.rb"
  end

  def create_magnitude_helper
    template "magnitude_helper.rb", "test/support/magnitude_helper.rb"
  end

  def inject_magnitude_helper
    inject_into_file "test/test_helper.rb", after: /class ActionDispatch::SystemTestCase\n/ do
      "  include MagnitudeHelper\n"
    end
  end

  def create_example_test
    template "todo_test.rb", "test/system/todo_test.rb"
  end
end

# lib/generators/templates/script_builder.rb
module Magnitude
  class ScriptBuilder
    def initialize(name)
      @name  = name
      @steps = []
    end

    def step(description, &block)
      builder = StepBuilder.new(description)
      builder.instance_eval(&block) if block
      @steps << builder
    end

    def to_script
      lines = [
        "import { test } from 'magnitude-test';",
        "",
        "test('#{@name}')"
      ]
      @steps.each { |s| lines.concat(s.to_js) }
      lines.join("\n")
    end
  end

  class StepBuilder
    def initialize(desc)
      @desc    = desc
      @actions = []
    end

    def visit(url = nil)
      target = url ? url.inspect : "process.env.BASE_URL!"
      @actions << ".visit(\#{target})"
    end

    def fill(selector, text)
      @actions << ".fill('\#{selector}', '\#{text}')"
    end

    def click(selector)
      @actions << ".click('\#{selector}')"
    end

    def check(text)
      @actions << ".check('\#{text}')"
    end

    def to_js
      ["  .step('\#{@desc}')"] + @actions.map { |a| "    \#{a}" }
    end
  end
end

# lib/generators/templates/magnitude_helper.rb
require 'open3'
require 'json'
require 'tempfile'
require_relative '../../../lib/magnitude/script_builder'

module MagnitudeHelper
  def self.included(base)
    base.extend ClassMethods
  end

  module ClassMethods
    def magnitude_test(name, &block)
      test(name) do
        result = MagnitudeHelper.run_magnitude(name, &block)
        assert_equal "success", result["status"]
      end
    end
  end

  def self.run_magnitude(name, &block)
    builder = Magnitude::ScriptBuilder.new(name)
    builder.instance_eval(&block)
    script = builder.to_script

    file = Tempfile.new(["magnitude", ".mag.ts"], binmode: true)
    file.write(script)
    file.flush

    server = Capybara.current_session.server
    raise "Capybara server not running" unless server
    base_url = "http://\#{server.host}:\#{server.port}"

    cmd = %W[npx magnitude run \#{file.path} --base-url \#{base_url} --json]
    stdout, stderr, status = Open3.capture3(*cmd)

    file.close!
    raise "Magnitude failed:\n\#{stderr}" unless status.success?
    JSON.parse(stdout)
  end
end

# lib/generators/templates/todo_test.rb
require "application_system_test_case"

class TodoTest < ApplicationSystemTestCase
  magnitude_test "create and complete a todo" do
    step "visit home page" do
      visit
    end

    step "add a new todo" do
      fill 'What needs to be done?', 'Buy milk'
      click 'Add'
    end

    step "mark it complete" do
      click 'input[type=checkbox]'
    end

    step "verify completion" do
      check 'Buy milk is marked completed'
    end
  end
end