An example of how the current Minitest does not let you describe choose the base class as its first scope.

minitest_spec_scope.rb

require 'rubygems'
gem 'minitest'
require 'minitest/autorun'

module MyTestHelpers
  
  def self.included(klass)
    klass.class_eval do
      extend ClassMethods
      include InstanceMethods
    end
  end
  
  module ClassMethods
    def foo?
      true
    end
  end
  
  module InstanceMethods
    def bar?
      false
    end
  end
  
end

# My spec helper test.

class MySpecClass < MiniTest::Spec
  include MyTestHelpers
end

class TestSpecClass < MySpecClass
  
  it 'should let me use instance helpers' do
    refute bar?
  end
  
  it 'should let me use class helpers' do
    assert self.class.foo?
  end
  
  describe 'describe scope' do
    
    it 'should let me use instance helpers' do
      refute bar?
    end

    it 'should let me use class helpers' do
      assert self.class.foo?
    end
    
  end
  
end

=begin

  1) Error:
test_0001_should_let_me_use_instance_helpers(describe scope):
NoMethodError: undefined method `bar?' for #<#<Class:0x1010dd818>:0x1010d1c70>
    /Users/kencollins/Desktop/TryMinitest/test.rb:75:in `test_0001_should_let_me_use_instance_helpers'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:817:in `__send__'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:817:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:664:in `_run_suite'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:657:in `map'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:657:in `_run_suite'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:647:in `_run_suites'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:647:in `map'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:647:in `_run_suites'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:623:in `_run_anything'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:778:in `run_tests'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:765:in `send'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:765:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:764:in `each'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:764:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:558:in `autorun'
    /Users/kencollins/Desktop/TryMinitest/test.rb:72

  2) Error:
test_0002_should_let_me_use_class_helpers(describe scope):
NoMethodError: undefined method `foo?' for describe scope:Class
    /Users/kencollins/Desktop/TryMinitest/test.rb:79:in `test_0002_should_let_me_use_class_helpers'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:817:in `__send__'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:817:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:664:in `_run_suite'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:657:in `map'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:657:in `_run_suite'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:647:in `_run_suites'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:647:in `map'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:647:in `_run_suites'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:623:in `_run_anything'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:778:in `run_tests'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:765:in `send'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:765:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:764:in `each'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:764:in `run'
    /opt/local/lib/ruby/gems/1.8/gems/minitest-2.0.2/lib/minitest/unit.rb:558:in `autorun'
    /Users/kencollins/Desktop/TryMinitest/test.rb:72

6 tests, 4 assertions, 0 failures, 2 errors, 0 skips

=end