Apparition makes it easy to do visual regression testing of your Rack-based webapp. It can run tests in headless or in real browsers using Selenium, at a variety of different sizes. Write specs like this:

# Take 1
remember "Home page" do
  its "default appearance" do
    visit '/'
    capture 'body'
  end

  its "user menu" do
    visit '/'
    find '.user-button'.click
    capture '.user-menu'
  end
end

# Take 2
## regression/home_page_spec.rb
remember "Default appearance" do
  it "should not change" do
    visit '/'
    capture 'body'
  end
  it "should look the same on modern browsers" do
    visit '/'
    capture('body').should look_the_same_in [:chrome, :firefox, :safari, :ie10]
  end
end

# I still don't know if this is the right way of tackling this
# problem... We may want to look at this more in terms of accepting visual changes
# as they come, and writing code that describes the diffs that we make people
# review.

# Take 3
## regression/home_page_spec.rb
remember "Default appearance" do
  it "should be reviewed" do
    visit '/'
    diff('body').across_versions
    # OR
    review_changes_to 'body'
  end
  it "should look the same on modern browsers" do
    visit '/'
    diff('body').in_browsers [:chrome, :firefox, :safari, :ie10]
    # OR
    review_differences_in('body').in_browsers [:chrome, :firefox, :safari, :ie10]
  end
end

and find out about inadvertent changes made to the appearance of your site right away. Apparition can test your site in all of the browsers and configurations that you care about, and tell you when any one of them changes. You can use it to spot check changes you make to your stylesheets, or integrate it into your continuous integration system to make sure all visual changes are approved. It's up to you.

The reasons for doing regression testing are the same as the reasons for doing any testing: Rapid iteration with increased confidence that your app still works. ...

We think visual regression testing is a good idea, and interest in projects such as PhantomCSS demonstrate that other people are interested in it, too. The problem is the lack of tools for a structured workflow. Apparition fixes that problem.

Add this line to your application's Gemfile:

gem 'apparition'

And then execute:

$ bundle

Or install it yourself as:

$ gem install apparition

TODO: Write usage instructions here

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request