This is my spec/helper.rb file:
require 'minitest/autorun'
require 'minitest/spec'
require_relative '../lib/launcher'
class MiniTest::Spec
  include MiniTest::Assertions
end
And this is the spec file:
require 'helper'
describe Launcher do
  it "should get the stdout" do
    out, err = capture_io do
      warn "You did a bad thing"
    end
    err.should =~ /bad/
  end
end
But when I run the spec:
± rake spec                                                                                                          
/Users/millisami/.rvm/rubies/ruby-1.9.3-p194/bin/ruby -S rspec ./spec/launcher_spec.rb -Ispec:lib
F
Failures:
  1) Launcher should be a launcher for cloud
     Failure/Error: out, err = capture_io do
     NoMethodError:
       undefined method `capture_io' for #<RSpec::Core::ExampleGroup::Nested_1:0x000001012a4840>
     # ./spec/launcher_spec.rb:5:in `block (2 levels) in <top (required)>'
Finished in 0.00044 seconds
1 example, 1 failure
Failed examples:
rspec ./spec/launcher_spec.rb:4 # launcher should be a launcher for cloud
rake aborted!
/Users/millisami/.rvm/rubies/ruby-1.9.3-p194/bin/ruby -S rspec ./spec/launcher_spec.rb -Ispec:lib failed
Tasks: TOP => spec
But when I do this with the default MiniTest::Unit way, it works? And why not the spec way?