class RSpec::Rails::AssertionDelegator

def assertion_instance
  @assertion_instance ||= build_assertion_instance
end

def initialize(*assertion_modules)
  assertion_class = Class.new(SimpleDelegator) do
    include Test::Unit::Assertions
    include ::RSpec::Rails::MinitestCounters
    assertion_modules.each { |mod| include mod }
  end
  super() do
    # @api private
    define_method :build_assertion_instance do
      assertion_class.new(self)
    end
    # @api private
    def assertion_instance
      @assertion_instance ||= build_assertion_instance
    end
    assertion_modules.each do |mod|
      mod.public_instance_methods.each do |method|
        next if method == :method_missing || method == "method_missing"
        class_eval <<-EOM, __FILE__, __LINE__ + 1
          def #{method}(*args, &block)
            assertion_instance.send(:#{method}, *args, &block)
          end
        EOM
      end
    end
  end
end