RSpec’s describe, context, and it blocks produce test output that reads like a specification. Combined with FactoryBot for test data and Capybara for integration testing, RSpec forms the standard Rails test stack. Its shared examples, custom matchers, and let/subject helpers enable DRY, expressive test suites.

Quick start

# For a Rails project
bundle add rspec-rails factory_bot_rails capybara --group test
rails generate rspec:install

# spec/models/post_spec.rb
require 'rails_helper'

RSpec.describe Post, type: :model do
  subject(:post) { build(:post) }

  describe 'validations' do
    it { is_expected.to validate_presence_of(:title) }
    it { is_expected.to validate_length_of(:title).is_at_least(3) }
    it { is_expected.to belong_to(:author) }
  end

  describe '#published?' do
    context 'when published_at is set' do
      let(:post) { build(:post, published_at: 1.day.ago) }
      it { is_expected.to be_published }
    end

    context 'when published_at is nil' do
      let(:post) { build(:post, published_at: nil) }
      it { is_expected.not_to be_published }
    end
  end
end

# spec/requests/posts_spec.rb
require 'rails_helper'

RSpec.describe 'Posts API', type: :request do
  let(:user) { create(:user) }
  let(:headers) { auth_headers(user) }

  describe 'GET /api/posts' do
    before { create_list(:post, 3, author: user) }

    it 'returns all posts' do
      get '/api/posts', headers: headers
      expect(response).to have_http_status(:ok)
      expect(json['data'].length).to eq(3)
    end
  end
end

When to use

RSpec is the standard for Ruby and Rails projects — most Rails codebases use it. Its BDD style produces tests that serve as living documentation. Minitest is a lighter alternative built into Ruby’s standard library, preferred by some teams for simplicity. For new Rails projects, RSpec + FactoryBot + Capybara is the proven stack. If you’re greenfielding a non-Rails Ruby project, Minitest’s simpler setup may be preferable.

RSpec

Quick start

When to use

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