Using Rspec from irb

This is a quick guide showing you necessary steps you should take to make rspec to work on irb

Lets start by loading rspec core and expectations

require 'rspec/core'         #this is what really runs your tests
require 'rspec/expectations' #readable syntax for checking properties of your code

We then include the matchers modules

include RSpec::Matchers

rspec will NOT automatically include this for you if you are using irb
With this we can now test out our expectations:

>> expect(1).to eq(1)
=> true

Whooohoo! You are good to go.. Not really, try this out

2.3.0 :003 > array_hashes = [{lol: nil}]
 => [{:lol=>nil}] 
2.3.0 :005 > include RSpec::Matchers
 => Object 
2.3.0 :006 > expect(array_hashes).to include(have_key(:lol))

Rspec error while using rspec include on irb
You will encounter an error as shown below:

TypeError: wrong argument type RSpec::Matchers::BuiltIn::Has (expected Module)
 from (irb):6:in `include’
 from (irb):6
 from /usr/local/rvm/rubies/ruby-2.3.0/bin/irb:11:in `<main>’

If you read closely into the error it expects a Module as an argument, this is because when using irb we are running in the main ruby object. This main ruby object has another method called include that has presidence over rspec’s include method
To work around this we can prepend RSpec::Matcher onto main’s singleton class:

$ irb
irb(main):001:0> require ‘rspec/expectations’
=> true
irb(main):002:0> singleton_class.prepend RSpec::Matchers
=> #<Class:#<Object:0x007ff08a8d6620>>
irb(main):003:0> array_hashes = [{lol: nil}]
=> [{:lol=>nil}]
irb(main):004:0> expect(array_hashes).to include(have_key(:lol))
=> true

We encountered this problem while doing a mob session at Agile Ventures

This is where we raised the issue https://github.com/rspec/rspec-expectations/issues/1018 on the rspec expectations github page and we got this hack