class ActionDispatch::AssertionResponse

does not have headers or a body.
does not inherit from Response because it doesn’t need it. That means it
This is a class that abstracts away an asserted response. It purposely

def code_and_name 

def code_and_name
  "#{code}: #{name}"
end

def code_from_name(name) 

def code_from_name(name)
  GENERIC_RESPONSE_CODES[name] || Rack::Utils.status_code(name)
end

def initialize(code_or_name)

indicating any 200-299 status code).
('404') or a response status range as a Symbol pseudo-code (:success,
Accepts a specific response status code as an Integer (404) or String 
def initialize(code_or_name)
  if code_or_name.is_a?(Symbol)
    @name = code_or_name
    @code = code_from_name(code_or_name)
  else
    @name = name_from_code(code_or_name)
    @code = code_or_name
  end
  raise ArgumentError, "Invalid response name: #{name}" if @code.nil?
  raise ArgumentError, "Invalid response code: #{code}" if @name.nil?
end

def name_from_code(code) 

def name_from_code(code)
  GENERIC_RESPONSE_CODES.invert[code] || Rack::Utils::HTTP_STATUS_CODES[code]
end