David Chelimsky

To make this happen, you need to require a few things:

require 'test/unit'
require 'rubygems'
gem 'rspec'
require 'spec/expectations'
require 'spec/matchers'

‘spec/expectations’ adds #should and #should_not to your objects. ‘spec/matchers’ provides RSpec’s Expression Matchers, which you then need to explicitly include in the TestCase:

class ThingTest < Test::Unit::TestCase
  include Spec::Matchers

Here’s an example with one passing and one failing test.

require 'test/unit'
require 'rubygems'
gem 'rspec'
require 'spec/expectations'
require 'spec/matchers'


class ThingTest < Test::Unit::TestCase
  include Spec::Matchers

def setup
    @thing = Thing.new
  end

def test_should_have_4_subthings #should fail
    @thing.should have(4).sub_things
  end

def test_should_have_3_subthings #should pass
    @thing.should have(3).sub_things
  end
end

class Thing
  def sub_things
    [1,2,3]
  end
end

Assuming that you have rspec-0.8.0 or better, this should produce the following output:

$ ruby thing_test.rb
Loaded suite thing_test
Started
.E
Finished in 0.000642 seconds.


1) Error:
test_should_have_4_subthings(ThingTest):
Spec::Expectations::ExpectationNotMetError: expected 4 sub_things, got 3
    /usr/local/lib/ruby/gems/1.8/gems/rspec-0.8.1/lib/spec/expectations.rb:55:in fail_with'
    /usr/local/lib/ruby/gems/1.8/gems/rspec-0.8.1/lib/spec/expectations/handler.rb:17:inhandle_matcher'
    /usr/local/lib/ruby/gems/1.8/gems/rspec-0.8.1/lib/spec/expectations/extensions/object.rb:28:in should'
    thing_test.rb:15:intest_should_have_4_subthings'

2 tests, 0 assertions, 0 failures, 1 errors

So now, although we’d like to see people who want to use RSpec using RSpec, this should lower the barrier to those who wish to migrate existing systems gradually.