rspec status code matchers for better failure messages

status_matchers.rb

# http://webcache.googleusercontent.com/search?q=cache:pM2SE1PFjwgJ:michal.muskala.eu/blog/2013/11/13/rspec-response-code-testing/+&cd=1&hl=en&ct=clnk&gl=us
# unless we're in a non-rack environment
# (which is unlikely when testing status codes, nonetheless possible)
require 'rack/utils'

module StatusMatchers

  # We will use this simple class as our matcher engine
  class BeStatus
    def initialize(status)
      @status = status
    end

    def matches?(target)
      if defined?(target.status)
        @target = target.status
      else
        @target = target
      end

      if @status.is_a?(Range)
        return @status.include?(@target)
      else
        return @target == @status
      end
    end

    def failure_message_for_should
      "expected #{@target} to be Status #{@status}"
    end

    def failure_message_for_should_not
      "expected #{@target} not to be in Status #{@status}"
    end
  end

  # We want to support all general status groups
  STATUS_CODE_RANGES = {
      informational: 100..199,
      success: 200..299,
      redirection: 300..399,
      client_error: 400..499,
      server_error: 500..599
  }

  # The Rack::Utils::SYMBOL_TO_STATUS_CODE contains all the
  # Rack::Utils::HTTP_STATUS_CODES already changed to symbols,
  # it's easier to use that
  SYMBOL_TO_STATUS_CODE =
      Rack::Utils::SYMBOL_TO_STATUS_CODE.merge(STATUS_CODE_RANGES)

  SYMBOL_TO_STATUS_CODE.each do |symbol, code|
    define_method("be_#{symbol}") { BeStatus.new(code) }
  end
end

RSpec.configure do |config|
  config.include StatusMatchers
end