Formulaic, testing forms.Easier.

I’ve been recently playing with thoughtbots Formulaic gem. I was frustrated and bored with the way how form in rails are tested. Luckily Formulaic reduced my frustration and boredom.

Life is good again :)

The problem

Let’s create rails post scaffold, for the n time (n tends to infinity).

  bin/rails generate scaffold post title body:text
   bin/rake db:migrate

Ok, now let’s write an integration test for adding a new post

require 'rails_helper'

feature 'User adds a new post' do
  scenario 'successfully, when title and body is entered'  do
    visit new_post_path

    fill_in 'Title', with: 'Strange kind of women'
    fill_in 'Body', with: 'The kind that gets written down in history'
    click_on 'Create Post'

    expect(page).to have_content 'Post was successfully created'
  end
end

When written on small test project like this, of course this is not too much of a problem, but in real world rails projects consisting of hundreds of forms this pattern of filling and exercising forms becomes pain in ass.
At least for me.

Also, I like to separate my test phases(setup, exercise, verify, teardown) with a new line, but writing tests like this I always ask myself does fill form fields belong to setup or exercise phase ?

Let’s give Formulaic a try!

First, in Gemfile add

gem 'formulaic', group: :test
bundle install

also, for Formulaic to work with rspec add following in rails_helper.rb

RSpec.configure do |config|
  config.include Formulaic::Dsl, type: :feature
end

Cool! Time to rewrite the previous test.

require 'rails_helper'

feature 'User adds a new post' do
  scenario 'successfully, when title and body is entered'  do
    visit new_post_path

    fill_form_and_submit(:post, 
      { title: 'Strange kind of women',
        body: 'The kind that gets written down in history' })

    expect(page).to have_content 'Post was successfully created'
  end
end

Much nicer, and hey, I don’t have to think in which phase filling fields belongs to.

If you are using fctory_girl this test becomes even more cooler:

require 'rails_helper'

feature 'User adds a new post' do
  scenario 'successfully, when title and body is entered'  do
    visit new_post_path

    fill_form_and_submit(:post, attributes_for(:post))

    expect(page).to have_content 'Post was successfully created'
  end
end

Caveats

Formulaic relies pretty heavily on the assumption that your application is using translations for SimpleForm and input helpers, using the simple_form.labels.<model>.<attribute> and helpers.submit.<model>.<action> conventions.

You can still use Formulaic by using strings as keys instead of symbols, which it knows to pass directly to fill_in rather than trying to find a translation. You’ll need to find submit buttons yourself since submit is a thin wrapper around I18n.t.

So, in our example I have to add some translations for this to work, but hey you will do that anyway.

helpers:
  submit:
    post:
      create: 'Create Post'

Also, formulaic assumes your forms don’t use AJAX, setting the wait time to 0. This can be configured using:

Formulaic.default_wait_time = 5

If you’ve read this whole post, I’m sure you have irresistible desire to listen to Deep Purple’s Strange Kind of Woman.

[Indulge yourself]

Dino Maric

Working class hero

Tweet Share