Rails 8 App: Comprehensive Guide 📑 to Write Controller Tests | 👓 Rspec – 20 Test Cases For Reference

group :test do
  gem 'rspec-rails'  # Main testing framework
  gem 'factory_bot_rails'  # For test data setup
  gem 'database_cleaner-active_record'  # Cleans test database
  gem 'faker'  # Generates fake data
  gem 'shoulda-matchers'  # Provides one-liner matchers for common Rails functions
end

bundle install
rails generate rspec:install

require 'rails_helper'

describe ArticlesController, type: :controller do
  describe 'GET #index' do
    it 'returns a successful response' do
      get :index
      expect(response).to have_http_status(:ok)
    end
  end
end

describe 'GET #show' do
  let(:article) { create(:article) }
  it 'returns the requested article' do
    get :show, params: { id: article.id }
    expect(response).to have_http_status(:ok)
    expect(assigns(:article)).to eq(article)
  end
end

describe 'GET #show' do
  it 'returns a 404 for an invalid ID' do
    get :show, params: { id: 9999 }
    expect(response).to have_http_status(:not_found)
  end
end

describe 'POST #create' do
  it 'creates a new article' do
    expect {
      post :create, params: { article: attributes_for(:article) }
    }.to change(Article, :count).by(1)
  end
end

describe 'POST #create' do
  it 'does not create an article with invalid parameters' do
    expect {
      post :create, params: { article: { title: '' } }
    }.not_to change(Article, :count)
  end
end

describe 'PATCH #update' do
  let(:article) { create(:article) }
  it 'updates an article' do
    patch :update, params: { id: article.id, article: { title: 'Updated' } }
    expect(article.reload.title).to eq('Updated')
  end
end

describe 'DELETE #destroy' do
  let!(:article) { create(:article) }
  it 'deletes an article' do
    expect {
      delete :destroy, params: { id: article.id }
    }.to change(Article, :count).by(-1)
  end
end

describe 'POST #create' do
  it 'redirects to the article show page' do
    post :create, params: { article: attributes_for(:article) }
    expect(response).to redirect_to(assigns(:article))
  end
end

describe 'GET #index' do
  it 'returns a JSON response' do
    get :index, format: :json
    expect(response.content_type).to eq('application/json')
  end
end

describe 'GET #show' do
  let(:article) { create(:article) }
  it 'returns the article in JSON format' do
    get :show, params: { id: article.id }, format: :json
    expect(response.content_type).to eq('application/json')
    expect(response.body).to include(article.title)
  end
end

describe 'PATCH #update' do
  let(:article) { create(:article) }
  it 'returns a 401 if user is not authorized' do
    patch :update, params: { id: article.id, article: { title: 'Updated' } }
    expect(response).to have_http_status(:unauthorized)
  end
end

describe 'POST #create' do
  it 'does not allow mass assignment of protected attributes' do
    expect {
      post :create, params: { article: { title: 'Valid', admin_only_field: true } }
    }.to raise_error(ActiveModel::ForbiddenAttributesError)
  end
end

describe 'DELETE #destroy' do
  it 'returns a 404 when the article does not exist' do
    delete :destroy, params: { id: 9999 }
    expect(response).to have_http_status(:not_found)
  end
end

describe 'GET #dashboard' do
  before { session[:user_id] = create(:user).id }
  it 'allows access to the dashboard' do
    get :dashboard
    expect(response).to have_http_status(:ok)
  end
end

describe 'GET #index' do
  before do
    10.times { get :index }
  end
  it 'returns a 429 Too Many Requests when rate limit is exceeded' do
    get :index
    expect(response).to have_http_status(:too_many_requests)
  end
end

describe 'GET #admin_dashboard' do
  context 'when user is admin' do
    let(:admin) { create(:user, role: :admin) }
    before { sign_in admin }
    it 'allows access' do
      get :admin_dashboard
      expect(response).to have_http_status(:ok)
    end
  end
  context 'when user is not admin' do
    let(:user) { create(:user, role: :user) }
    before { sign_in user }
    it 'redirects to home' do
      get :admin_dashboard
      expect(response).to redirect_to(root_path)
    end
  end
end

describe 'PATCH #update' do
  let(:article) { create(:article) }
  it 'updates an article and responds with Turbo Stream' do
    patch :update, params: { id: article.id, article: { title: 'Updated' } }, format: :turbo_stream
    expect(response.media_type).to eq Mime[:turbo_stream]
  end
end

describe 'WebSocket Connection' do
  let(:user) { create(:user) }
  
  before do
    sign_in user
  end

  it 'successfully subscribes to a channel' do
    subscribe room_id: 1
    expect(subscription).to be_confirmed
    expect(subscription).to have_stream_from("chat_1")
  end
end

describe 'POST #create in nested resource' do
  let(:user) { create(:user) }
  let(:post) { create(:post, user: user) }

  it 'creates a comment under the correct post' do
    expect {
      post :create, params: { post_id: post.id, comment: { body: 'Nice post!' } }
    }.to change(post.comments, :count).by(1)
  end
end

describe 'PATCH #update (multi-step form)' do
  let(:user) { create(:user, step: 'personal_info') }

  it 'advances the user to the next step in a multi-step form' do
    patch :update, params: { id: user.id, user: { step: 'address_info' } }
    expect(user.reload.step).to eq('address_info')
  end
end