rspec matcher for decorator

decorations.rb

# spec/support/matchers/decorations.rb
module Support
  module Matchers
    module Decorations
      extend RSpec::Matchers::DSL

      def decorated_object_attributes(model, klass: nil, user: nil, context: nil)
        context ||= {}

        attrs = { object: model }
        attrs[:class] = klass if klass

        context[:user] = user if user
        attrs[:context] = a_hash_including(context) if context.any?

        an_object_having_attributes(**attrs)
      end

      matcher :be_decorated do |model|
        match(notify_expectation_failures: true) do |decorated|
          expect(decorated).to match(
            decorated_object_attributes(model, klass: @class, user: @user, context: @context)
          )
        end

        chain :with_class do |klass|
          @class = klass
        end

        chain :with_context do |context|
          @context = context
        end

        chain :with_user do |user|
          @user = user
        end
      end

      RSpec.configure do |rspec|
        rspec.include self, type: :operation
        rspec.include self, type: :decorator
      end
    end
  end
end