rspec-testing

RSpec Testing for Rails

Overview

Write comprehensive, maintainable RSpec tests following industry best practices. This skill combines guidance from Better Specs and thoughtbot's testing guides to produce high-quality test coverage for Rails applications.

Core Testing Principles

1. Test-Driven Development (TDD)

Follow the Red-Green-Refactor cycle:

• Red: Write failing tests that define expected behavior
• Green: Implement minimal code to make tests pass
• Refactor: Improve code while tests continue to pass

2. Test Structure (Arrange-Act-Assert)

Organize tests with clear phases separated by newlines:

it 'creates a new article' do
  # Arrange - set up test data
  user = create(:user)
  attributes = {title: 'Test Article', body: 'Content here'}

  # Act - perform the action
  article = Article.create(attributes)

  # Assert - verify the outcome
  expect(article).to be_persisted
  expect(article.title).to eq('Test Article')
end

3. Single Responsibility

Each test should verify one behavior. For unit tests, use one expectation per test. For integration tests, multiple expectations are acceptable when testing a complete flow.

4. Test Real Behavior

Avoid over-mocking. Test actual application behavior when possible. Only stub external services, slow operations, and dependencies outside your control.

Test Type Decision Tree

When to Write Model Specs

Use model specs (spec/models/) for:

• Validations
• Associations
• Scopes
• Instance methods
• Class methods
• Enums and constants
• Database constraints

Example:

# spec/models/article_spec.rb
RSpec.describe Article do
  describe 'validations' do
    it 'validates presence of title' do
      article = build(:article, title: nil)
      expect(article).not_to be_valid
      expect(article.errors[:title]).to include("can't be blank")
    end
  end

  describe 'associations' do
    it { is_expected.to belong_to(:user) }
    it { is_expected.to have_many(:comments) }
  end

  describe '#published?' do
    it 'returns true when status is published' do
      article = build(:article, status: :published)
      expect(article.published?).to be true
    end
  end
end