Move brand_helper and add test file

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
-* Add an optional `canonical` meta tag.
+* Add an optional `canonical` meta tag (PR #302)
+* Iterate branding model (PR #300)
 
 # 7.2.0
 

lib/govuk_publishing_components.rb

@@ -1,6 +1,5 @@
 require "govuk_publishing_components/config"
 require "govuk_publishing_components/engine"
-require "govuk_publishing_components/presenters/brand_helper"
 require "govuk_publishing_components/presenters/contextual_navigation"
 require "govuk_publishing_components/presenters/related_navigation_helper"
 require "govuk_publishing_components/presenters/step_by_step_nav_helper"
@@ -15,6 +14,7 @@
 require "govuk_publishing_components/presenters/content_item"
 
 require "govuk_publishing_components/app_helpers/taxon_breadcrumbs"
+require "govuk_publishing_components/app_helpers/brand_helper"
 
 module GovukPublishingComponents
 end

lib/govuk_publishing_components/presenters/brand_helper.rb → lib/govuk_publishing_components/app_helpers/brand_helper.rb

@@ -1,10 +1,14 @@
 module GovukPublishingComponents
-  module Presenters
+  module AppHelpers
     class BrandHelper
       def initialize(brand)
         @brand = brand if brand
       end
 
+      # Apply government organisation branding to individual components, specifically
+      # link colour and border colour
+      # see https://github.com/alphagov/govuk_publishing_components/blob/master/docs/component_branding.md
+
       def brand_class
         "brand--#{@brand}" if @brand
       end

spec/lib/app_helpers/brand_helper_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+RSpec.describe GovukPublishingComponents::AppHelpers::BrandHelper do
+  describe "Brand helper" do
+    it "returns nothing if no brand is specified" do
+      brand = GovukPublishingComponents::AppHelpers::BrandHelper.new(nil)
+
+      expect(brand.brand_class).to eql(nil)
+      expect(brand.border_color_class).to eql(nil)
+      expect(brand.color_class).to eql(nil)
+    end
+
+    it "returns the expected brand" do
+      brand = GovukPublishingComponents::AppHelpers::BrandHelper.new('attorney-generals-office')
+
+      expect(brand.brand_class).to eql('brand--attorney-generals-office')
+      expect(brand.border_color_class).to eql('brand__border-color')
+      expect(brand.color_class).to eql('brand__color')
+    end
+  end
+end