Inline Rails Application example

rails_inline.rb

# from https://github.com/rails/rails/issues/42835#issuecomment-884768835
# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", "6.1.3.2"
end

require "action_controller/railtie"

class TestApp < Rails::Application
  config.root = __dir__
  config.hosts << "example.org"
  secrets.secret_key_base = "secret_key_base"

  config.logger = Logger.new($stdout)
  Rails.logger  = config.logger

  routes.draw do
    get "/" => "test#index"
  end
end

class CustomObject
  def to_json(_options = nil)
    '"#to_json"'
  end
end

class TestController < ActionController::Base
  include Rails.application.routes.url_helpers

  def index
    render json: CustomObject.new
  end
end

require "minitest/autorun"
require "rack/test"

class BugTest < Minitest::Test
  include Rack::Test::Methods

  def test_returns_success
    get "/"
    assert last_response.ok?
    assert_equal '"#to_json"', last_response.body
  end

  private
    def app
      Rails.application
    end
end