minitest/spec + shared examples

minitest_shared.rb

require 'minitest/autorun'

class MiniTest::Spec
  def self.include_tests(tests)
    tests.each do |args, block|
      it(*args, &block)
    end
  end
end

class Module
  def included_tests
    @included_tests ||= []
  end

  def it(*args, &block)
    included_tests << [args, block]
    self.class.send(:define_method, :included) do |base|
      base.include_tests(included_tests)
    end
  end

  alias :specify :it
end

module SupportsCount
  it "returns a natural number" do
    assert_operator @object.count, :>=, 0
  end

  it "returns an integer" do
    assert_kind_of Integer, @object.count
  end
end

describe Array do
  include SupportsCount

  before do
    @object = []
  end
end