Validate uniqueness with Rspec matchers (not shoulda)

gistfile1.rb

describe 'Category' do
  
  context '#create' do
    before(:all) do
       @properties    = {:code => 'TST', :description => 'Test Category'}
       @category      = Category.create(@properties)
       @same_category = Category.create(@properties)
    end

    context 'When right properties given' do
      it 'the category gets persisted' do
        @category.should be_persisted
      end

      it 'unless code is not unique' do
        @same_category.should_not be_persisted
        @same_category.should have_at_least(1).errors_on(:code)
      end
    end
  end

end