Change feature flag names to represent headers set at the CDN

This commit changes the feature flag names used in `FeatureFlagNames` to represent headers as we set them at the CDN. This allows us to output response headers for the feature flags and in the `Vary` header which are consistent with others headers that we set.

app/models/http_feature_flags.rb

@@ -3,19 +3,25 @@ def initialize
     @feature_flags = {}
   end
 
-  def add_http_feature_flag(header_name, val)
-    @feature_flags[header_name] = val
+  def add_http_feature_flag(feature_flag_name, val)
+    @feature_flags[get_header_name(feature_flag_name)] = val
   end
 
-  def get_feature_flag(header_name)
-    @feature_flags[header_name]
+  def get_feature_flag(feature_flag_name)
+    @feature_flags[get_header_name(feature_flag_name)]
   end
 
-  def feature_enabled?(header_name, request_headers)
-    @feature_flags.has_key?(header_name) && @feature_flags[header_name] == request_headers[header_name]
+  def feature_enabled?(feature_flag_name, request_headers)
+    get_feature_flag(feature_flag_name) == request_headers[get_header_name(feature_flag_name)]
   end
 
   def self.instance
     @instance ||= HttpFeatureFlags.new
   end
+
+private
+
+  def get_header_name(feature_flag_name)
+    "HTTP_#{feature_flag_name.upcase.tr('-', '_')}"
+  end
 end

config/initializers/feature_flags.rb

@@ -1,6 +1,6 @@
 module FeatureFlagNames
   def self.recommended_related_links
-    'HTTP_GOVUK_USE_RECOMMENDED_RELATED_LINKS'
+    'Govuk-Use-Recommended-Related-Links'
   end
 end
 

test/controllers/content_items_controller_test.rb

@@ -141,7 +141,7 @@ class ContentItemsControllerTest < ActionController::TestCase
 
   test "gets item from content store and keep existing ordered_related_items when feature flag header is specified but links already exist" do
     HttpFeatureFlags.instance.add_http_feature_flag(FeatureFlagNames.recommended_related_links, 'true')
-    request.headers[FeatureFlagNames.recommended_related_links] = 'true'
+    request.headers["HTTP_GOVUK_USE_RECOMMENDED_RELATED_LINKS"] = 'true'
 
     content_item = content_store_has_schema_example('guide', 'guide')
 
@@ -154,7 +154,7 @@ class ContentItemsControllerTest < ActionController::TestCase
 
   test "gets item from content store and keeps ordered_related_items when feature flag header is specified but recommended links turned off" do
     HttpFeatureFlags.instance.add_http_feature_flag(FeatureFlagNames.recommended_related_links, 'false')
-    request.headers[FeatureFlagNames.recommended_related_links] = 'true'
+    request.headers["HTTP_GOVUK_USE_RECOMMENDED_RELATED_LINKS"] = 'true'
 
     content_item = content_store_has_schema_example('case_study', 'case_study')
 
@@ -167,7 +167,7 @@ class ContentItemsControllerTest < ActionController::TestCase
 
   test "gets item from content store and replaces ordered_related_items when feature flag header is specified and there are no existing links" do
     HttpFeatureFlags.instance.add_http_feature_flag(FeatureFlagNames.recommended_related_links, 'true')
-    request.headers[FeatureFlagNames.recommended_related_links] = 'true'
+    request.headers["HTTP_GOVUK_USE_RECOMMENDED_RELATED_LINKS"] = 'true'
 
     content_item = content_store_has_schema_example('case_study', 'case_study')
 

test/models/http_feature_flags_test.rb

@@ -6,26 +6,26 @@ class HttpFeatureFlagsTest < ActiveSupport::TestCase
     instance.add_http_feature_flag('TEST_HEADER', 'show')
 
     new_instance = HttpFeatureFlags.instance
-    feature_enabled = new_instance.feature_enabled?('TEST_HEADER', 'TEST_HEADER' => 'show')
+    feature_enabled = new_instance.feature_enabled?('TEST_HEADER', 'HTTP_TEST_HEADER' => 'show')
 
     assert_equal(true, feature_enabled)
   end
 
   test 'add_http_feature_flag should set a new feature flag' do
     instance = HttpFeatureFlags.new
 
-    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'USE_MAGIC' => 'only_at_weekends')
+    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'HTTP_USE_MAGIC' => 'only_at_weekends')
     assert_equal(false, feature_enabled)
 
     instance.add_http_feature_flag('USE_MAGIC', 'only_at_weekends')
-    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'USE_MAGIC' => 'only_at_weekends')
+    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'HTTP_USE_MAGIC' => 'only_at_weekends')
     assert_equal(true, feature_enabled)
   end
 
   test 'feature_enabled? should return false when feature flag has not been set' do
     instance = HttpFeatureFlags.new
 
-    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'USE_MAGIC' => 'only_at_weekends')
+    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'HTTP_USE_MAGIC' => 'only_at_weekends')
     assert_equal(false, feature_enabled)
   end
 
@@ -41,15 +41,15 @@ class HttpFeatureFlagsTest < ActiveSupport::TestCase
     instance = HttpFeatureFlags.new
 
     instance.add_http_feature_flag('USE_MAGIC', 'only_at_weekends')
-    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'USE_MAGIC' => 'all_the_time')
+    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'HTTP_USE_MAGIC' => 'all_the_time')
     assert_equal(false, feature_enabled)
   end
 
   test 'feature_enabled? should return true when headers has been set and matches specified value' do
     instance = HttpFeatureFlags.new
 
     instance.add_http_feature_flag('USE_MAGIC', 'only_at_weekends')
-    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'USE_MAGIC' => 'only_at_weekends')
+    feature_enabled = instance.feature_enabled?('USE_MAGIC', 'HTTP_USE_MAGIC' => 'only_at_weekends')
     assert_equal(true, feature_enabled)
   end