Writing unit tests in Ruby for a REST API

You might have a look at this approach http://anthonyeden.com/2013/07/10/testing-rest-apis-with-cucumber-and-rack.html

although many might say that using Cucumber is really more application or Acceptance testing and not unit testing, it does contain an approach to creating the HTTP headers and forming the http request, which I'm guessing might be where you are stuck?

Personally I don't have a problem with that since if you are truely going to unit test the API, you'd likely have to mock any units of code the api might be talking with (e.g. however you are persisting the data)

Seeing as I'm a QA guy not a dev, I'd be perfectly happy with using cucumber and testing it at that level, but I also greatly appreciate it when devs unit test, so while you might use rSpec instead of Cuke, perhaps the tip towards 'rack test' will be useful to what you are trying to accomplish.

The best way is a matter of opinion :) Personally, I like simple and clean. With tools like minitest, Watir and rest-client, you can put together a very simple test of both your REST interface as well as testing your web service through actual browsers (all major browsers are supported).

#!/usr/bin/ruby
#
# Requires that you have installed the following gem packages: 
# json, minitest, watir, watir-webdrive, rest-client
# To use Chrome, you need to install chromedriver on your path

require 'rubygems'
require 'rest-client'  
require 'json'
require 'pp'
require 'minitest/autorun'
require 'watir'
require 'watir-webdriver'

class TestReportSystem < MiniTest::Unit::TestCase
   def setup
      @browser = Watir::Browser.new :chrome # Defaults to firefox. Can do Safari and IE too.
      # Log in here.....
   end

   def teardown
      @browser.close
   end

   def test_report_lists   # For minitest, the method names need to start with test
      response = RestClient.get 'http://localhost:8080/reporter/reports/getReportList'
      assert_equal response.code,200
      parsed = JSON.parse response.to_str
      assert_equal parsed.length, 3 # There are 3 reports available on the test server
   end

   def test_on_browser
      @browser.goto 'http://localhost:8080/reporter/exampleReport/simple/genReport?month=Aug&year=2012'
      assert(@browser.text.include?('Report for Aug 2012'))
   end
end

Run the test cases by simply executing the script. There are many other testing systems and REST clients for Ruby which can be put to work in a similar way.