Model tests in Ruby on Rails - Mini Project: Build & Apply

Model tests

📖 Scenario: You are building a simple Rails app to manage books in a library. Each book has a title and an author. You want to make sure your model works correctly by writing tests.

🎯 Goal: Write model tests for the Book model to check that it validates presence of title and author.

📋 What You'll Learn

Create a Book model with title and author attributes

Add presence validations for title and author

Write model tests to check these validations using RSpec

💡 Why This Matters

🌍 Real World

Model tests help ensure your data rules work correctly before saving to the database, preventing bad data and bugs.

💼 Career

Writing model tests is a key skill for Rails developers to maintain reliable and maintainable applications.

1

Create the Book model with attributes

Create a Rails model called Book with string attributes title and author using a migration.

Ruby on Rails

# Generate the Book model with title and author attributes
# Your code here

Need a hint?

Use rails generate model Book title:string author:string to create the model and migration.

2

Add presence validations to Book model

In the Book model, add presence validations for the title and author attributes using validates :title, presence: true and validates :author, presence: true.

Ruby on Rails

class Book < ApplicationRecord
  # Add presence validations for title and author
  # Your code here
end

Need a hint?

Use validates :attribute, presence: true for each attribute.

3

Create RSpec model test file for Book

Create a new RSpec test file spec/models/book_spec.rb with a describe Book block to hold your model tests.

Ruby on Rails

# Create spec/models/book_spec.rb
# Add describe block for Book model
# Your code here

Need a hint?

Use describe Book, type: :model do ... end to start the test file.

4

Write presence validation tests for Book model

Inside the describe Book block, write two tests using it blocks to check that title and author must be present. Use should validate_presence_of(:title) and should validate_presence_of(:author) matchers.

Ruby on Rails

describe Book, type: :model do
  # Add tests for presence validations of title and author
  # Your code here
end

Need a hint?

Use it { should validate_presence_of(:attribute) } syntax from shoulda-matchers gem.