RSpec Testing in Ruby on Rails: The Basics

George Tobias
May 25, 2023


As a Ruby on Rails developer, writing efficient and reliable test cases is essential to ensure the quality and functionality of your applications. One of the most popular testing frameworks used in the Ruby on Rails ecosystem is RSpec. In this article, we’ll explore the basics of RSpec testing and how to use it to write effective test cases for your applications.

Section 1: What is RSpec Testing?

RSpec is a behaviour-driven development (BDD) testing framework that provides a structure for writing test cases in a more readable and organised manner. It allows developers to write tests that describe the behaviour of their application in a more human-readable language, making it easier to understand and maintain the codebase.

Section 2: Setting up RSpec in a Ruby on Rails Application

Before we start writing tests using RSpec, we need to set it up in our Ruby on Rails application. We can do this by adding the RSpec gem to our Gemfile and running the installation command:


# Run against this stable release
group :development, :test do
  gem 'rspec-rails', '~> 6.0.0'

# Or, run against the main branch
# (requires main-branch versions of all related RSpec libraries)
group :development, :test do
  %w[rspec-core rspec-expectations rspec-mocks rspec-rails rspec-support].each do |lib|
    gem lib, git: "{lib}.git", branch: 'main'



# Download and install
$ bundle install

# Generate boilerplate configuration files
# (check the comments in each generated file for more information)
$ rails generate rspec:install
      create  .rspec
››      create  spec
      create  spec/spec_helper.rb
      create  spec/rails_helper.rb

This will create the necessary files and directories for RSpec testing in our Rails application.

Section 3: Writing RSpec Test Cases

RSpec provides a variety of matchers and expectations that we can use to write our test cases. These matchers make it easy to test different aspects of our application, such as database queries, HTTP requests, and view rendering.

Let’s say we have a PostsController in our Ruby on Rails application with a create action that accepts a post’s title and body as parameters. We want to test that this action creates a new post record in the database when called with valid parameters. Here’s how we can write a request spec for this scenario using RSpec:

In your posts_spec.rb file, add the following code:



require 'rails_helper'

RSpec.describe "Posts", type: :request do
  describe "POST /posts" do
    context "with valid parameters" do
      let(:post_params) do
        { title: "My Post", body: "Lorem ipsum dolor sit amet." }

      it "creates a new post" do
        expect {
          post "/posts", params: { post: post_params }
        }.to change(Post, :count).by(1)


Let’s break down what’s happening here:

  • We first require rails_helper to load the Rails environment and RSpec configuration.
  • We then define our Posts request spec and set its type to :request.
  • Inside the request spec, we describe the POST /posts endpoint using describe.
  • We then define a context for when the request is made with valid parameters.
  • We create a post_params variable to hold the valid post parameters.
  • Finally, we use RSpec’s expect syntax to verify that calling POST /posts with the post_params creates a new Post record in the database.

Run the request spec by running the following command in your terminal:


$ bundle exec rspec spec/requests/posts_spec.rb

Section 4: Best Practices for RSpec Testing

To write efficient and reliable test cases using RSpec, we need to follow some best practices. Here are some tips to keep in mind:

Use descriptive test names that clearly describe the behavior being tested and should (almost) read like plain English. A good way to check this would be to run the spec in documentation format:


$ bundle exec rspec --format documentation spec/requests/posts_spec.rb

  POST /posts
    with valid parameters
      creates a new post

Write small, focused test cases that test one aspect of the application at a time. Use factories or fixtures to generate test data instead of relying on real data. Use before and after hooks to set up and tear down test data. Use shared examples and context blocks to group related test cases and improve readability.

Section 5: Conclusion

RSpec is a powerful testing framework that can help Ruby on Rails developers write efficient and reliable test cases for their applications. By following best practices and using the variety of matchers and expectations provided by RSpec, developers can ensure the quality and functionality of their applications.