Using TDD to create a simple rails project framework

Using TDD to create a simple rails project framework

TDD for beginners can be a challenge particularly in understanding the logic to create that first test. Using spikes to learn how to create a feature and then write a test can help to support the learning process. Likewise digging around in a functioning environment can also be a great tool to help understand and application and write functional tests. The following instructions step through creating a simple rails blog project with learning to write and using this to drive development the focus. Using the “git worktree” feature and some basic rails scripts to create a working rails blog application creates a learning environment to help facilitate writing tests that can be transferred and used to drive TDD in a new rails project.

Create a simple rails project framework :

rails new [rails_project_name] --database=postgresql --minimal --skip-test

Move into the folder generated

cd [rails_project_name]
git status

remove the git init when running the “rails new” script it will be set up up a git repo (ie do a git init) we want to remove this if the folder we working is already a git repo..

rm -rf .git

Run your rails program

rails server

NOTE If the postgresql database is not running error will appear when local host in browser id opened. To start the postgresql if you are using brew

brew services start postgresql@12

Create your database

bin/rails db:create

Adding rspec and capybara test framework

  1. Add the following gems:
  • Gemfile
#rspec and capybara test suite
  group :test do
    gem 'capybara'
    gem 'rspec-rails'
    gem 'capybara-inline-screenshot'
    gem 'selenium-webdriver'
    gem 'webdrivers'
    gem 'rspec-example_steps'
  1. run on command line
rails generate rspec:install
  1. Add/ammend the following files:
  • spec/rails_helper.rb
    • uncomment out on approx line 23
Dir[Rails.root.join('spec', 'support', '**', '*.rb')].sort.each { |f| require f }
  • spec/support/capybara.rb
    • Create the following folder and file and add content to the capybara.rb file:
require 'capybara/rspec'
require 'capybara/rails'
require 'capybara-inline-screenshot/rspec'

Capybara.javascript_driver = :selenium_chrome

Capybara::Screenshot.register_driver(:selenium_chrome) do |driver, path|

At this point we have a basic empty rails application with a test framework created.

Create a exploration a blog environment to write a test

At this point we want to create a temporary copy of the project and create a simple blog. Having separate terminal windows/tabs open for the main branch and a separate on for the worktree will enable simple moving between the environments.

Create a worktree

In new terminal window/tab remain in the [rails_project_name] folder

 git worktree add [blog-create-learning]
 cd [blog-create-learning]

there is now a worktree setup of the repo folder. Assess the [rails_project_name] folder on the blog-create-learning worktree branch.

Run the [blog-create-learning] “worktree” on another port:

bin/rails server --port 3030

Create a simple blog with title and text

rails generate scaffold Article title:string text:text
bin/rails db:migrate

make a quick change so the landing page starts at the /articles….

  • config/routes.rb
    • uncomment out line 6
  root "articles#index"

on the worktree we now have a functioning blog but no tests… use this environment to create a you first test. Explore the behaviour from landing page to create a new blog entry and generate a integration test….

When you have finished using the worktree environment it can be removed but a branch will still exist after running the remove command:

git worktree remove [blog-create-learning]

if the explore branch is not needed again:

git branch -d [blog-create-learning]

Writing tests overview:

For the simple blog above, here is a starting point for a integration test that can be built upon and used as a starting point in your “naked” rails application. Add the following file and content:

  • spec/features/create_a_blog_spec.rb
require 'rails_helper'

feature 'creating blogs', js: true do
  scenario 'new user creates a blog post' do
    When "user visits the app" do
      visit root_path

    Then "they see a new article link" do
      expect(page).to have_text('New article')

    When "user clicks the link" do
      click_link('New article')

    Then "user successfully navigates to a new blog entry" do
      ).to eq '/articles/new'

run the test on command line


You have a passing test (starting point) that can be now applied to your “naked” project environment…