Running karma js with rails asset pipeline / sprockets


# test/karma.conf.js
...
    basePath: '<%= Bundler.root %>',
...
    files: [
      '<%= resolve_asset('vis.js') %>',
      'app/assets/javascripts/app.js',
      'test/**/*_spec.js'
    ],

# Rakefile
namespace :test do
  task js: :environment do
    with_tmp_karma_config do |config|
      sh "./node_modules/karma/bin/karma start #{config} --single-run"
    end
  end

  private

  def with_tmp_karma_config
    Tempfile.open('karma.js') do |f|
      f.write ERB.new(File.read('test/karma.conf.js')).result(binding)
      f.flush
      yield f.path
    end
  end

  def resolve_asset(file)
    Rails.application.assets.find_asset(file).to_a.first.pathname.to_s
  end
end

Development checks for fast boottime

A few simple checks to make sure we are not regressing into slow boot times by preloading to many things. Needs to be the last initializer so it catches what all the others are doing -> zz.rb

Code


# config/initializers/zz.rb
if Rails.env.development?
  # make sure we do not regress into slow startup time by preloading to much
  Rails.configuration.after_initialize do
    [
      ActiveRecord::Base.send(:descendants).map(&:name),
      ActionController::Base.descendants.map(&:name),
      (File.basename($0) != "rake" && defined?(Rake) && "rake"),
    ].compact.flatten.each { |c| raise "#{c} should not be loaded" }
  end
end

Result


config/initializers/zz.rb:9:in `block (2 levels) in ': 
User should not be loaded (RuntimeError)

Rails 3: Faster startup by not eager loading engines

Engine eager load by default on rails 3, so lets turn that off to save some precious startup time.

# config/environments/test.rb + development.rb
config.eager_load = false

# config/application.rb
if !config.eager_load && Rails::VERSION::MAJOR == 3
  Rails::Railtie.descendants.each do |railtie|
    railtie.class_eval { def eager_load!; end }
  end
end

Test startup time -33% by making fixtures not require

Small little patch, big test improvements 🙂

# do not load every class when using fixtures :all -> speedup
ActiveRecord::TestFixtures::ClassMethods.class_eval do
 def require_fixture_classes(*args)
 end
end

FYI merged Rails PR, will be in Rails 5, maybe 4.2.x 🙂

Stop rails from swallowing after_commit exceptions

Problem
By default rails just swallows any exception raised in after_commit blocks.

Solution
Send these exceptions to and exception service to get notified (Airbrake / Rollbar etc).

Gem
https://github.com/grosser/after_commit_exception_notification

Copy-paste

module Foo
  module CommittedWithExceptions
    def committed!
      super
    rescue Exception => e # same as active_record/connection_adapters/abstract/database_statements.rb:370
      ExceptionService.report("after_commit exception", e)
      raise
    end
  end
end

ActiveRecord::Base.include Foo::CommittedWithExceptions

Michael Grosser, the Blog

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Tag Archives: Rails