JSON Schema matcher

schema_matcher.rb

# spec/support/schema_matcher.rb
class Schema
  @definitions = {}

  def self.define(name, &block)
    @definitions[name] = block.call
  end

  def self.defined?(name)
    @definitions.key?(name)
  end

  def self.resolve(name)
    @definitions.fetch(name, {})
  end
end

RSpec::Matchers.define :match_schema do |name|
  match do |response|
    schema = Schema.resolve(name)
    JSON::Validator.validate!(schema, response.body, strict: true)
  end
end

users.rb

# spec/support/schemas/users.rb
Schema.define('users') do
  {
    type: :object,
    properties: {
      users: {
        type: :array,
        items: {
          type: :object,
          properties: {
            name: {
              type: :string
            },
            id: {
              type: :number
            }
          }
        }
      }
    }
  }
end

users_spec.rb

# spec/request/users_spec.rb
require 'spec_helper'

describe 'Users' do
  it 'validates' do
    response = OpenStruct.new
    response.body = <<-JSON
      {
        "users": [
          {
            "name": "John Doe",
            "id": 1
          }
        ]
      }
JSON
    expect(response).to match_schema('users')
  end
end