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Testing JSON Jbuilder Responses in Rails Controllers

Testing JSON Jbuilder Responses in Rails Controllers

Introduction:

When building Rails applications, it’s essential to test the responses of our controllers, especially when generating JSON output using Jbuilder templates. In this article, we’ll explore how to effectively test JSON Jbuilder responses for a Book model’s show action in the BooksController.

Setting up the Scenario:

Consider a Book model with attributes such as id, title, author_name, and genre. We have a show action in the BooksController that fetches a book by its ID.

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# == Schema Information
#
# Table name: books
#
#  id          :bigint           not null, primary key
#  author_name :string
#  genere      :string
#  title       :string
#  created_at  :datetime         not null
#  updated_at  :datetime         not null
#
class Book < ApplicationRecord
end

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class BooksController < ApplicationController
  def show
    @book = Book.find_by(id: params[:id])
  end
end

Writing the Jbuilder Template:

To generate the JSON response, we use a Jbuilder template for the show action. The template specifies the attributes to include in the response, such as id, title, author_name, and genre.

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json.id @book.id
json.title @book.title
json.author_name @book.author_name
json.genere @book.genere

# Sample output of url: /books/:id could be:

{
    "id": 1,
    "title": "The Fault in Our Stars",
    "author_name": "John Green",
    "genere": "Fiction"
}

Testing the JSON Jbuilder Response:

To test the JSON response, we need to write controller tests using RSpec. By including the render_views directive, we can render the response from the Jbuilder template.

In the test case, we make a GET request to the show action, passing the book’s ID and specifying the response format as JSON. We then parse the response body using JSON.parse and can assert against the expected values.

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require 'rails_helper'

RSpec.describe BooksController, type: :controller do
  render_views

  describe "GET show" do
    it "returns a JSON response with the attributes specified in the Jbuilder serializer" do
      book = Book.create(title: "The Fault in Our Stars", author_name: "John Green", genre: "Fiction")

      get :show, params: { id: book.id }, format: :json

      parsed_body = JSON.parse(response.body)
      expect(parsed_body["id"]).to eq(book.id)
      expect(parsed_body["title"]).to eq(book.title)
      expect(parsed_body["author_name"]).to eq(book.author_name)
      expect(parsed_body["genre"]).to eq(book.genre)
    end
  end
end

By executing this test, we can ensure that the JSON response from the show action contains the expected attributes and values as specified in the Jbuilder template.

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