Fix component wrapper rel option

lib/govuk_publishing_components/presenters/component_wrapper_helper.rb

@@ -240,7 +240,8 @@ def check_rel_is_valid(rel_attribute)
         return if rel_attribute.blank?
 
         options = %w[alternate author bookmark canonical dns-prefetch external expect help icon license manifest me modulepreload next nofollow noopener noreferrer opener pingback preconnect prefetch preload prerender prev privacy-policy search stylesheet tag terms-of-service]
-        unless options.include? rel_attribute
+        rel_array = rel_attribute.split(" ")
+        unless rel_array.all? { |r| options.include? r }
           raise(ArgumentError, "rel attribute (#{rel_attribute}) is not recognised")
         end
       end

spec/lib/govuk_publishing_components/components/component_wrapper_helper_spec.rb

@@ -396,11 +396,23 @@
         }.to raise_error(ArgumentError, error)
       end
 
-      it "accepts valid rel value" do
+      it "accepts a valid rel value" do
         component_helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow")
         expect(component_helper.all_attributes[:rel]).to eql("nofollow")
       end
 
+      it "accepts multiple valid rel values" do
+        component_helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow noreferrer")
+        expect(component_helper.all_attributes[:rel]).to eql("nofollow noreferrer")
+      end
+
+      it "does not accept multiple rel values if one of them is invalid" do
+        error = "rel attribute (nofollow noreferrer potato) is not recognised"
+        expect {
+          GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow noreferrer potato")
+        }.to raise_error(ArgumentError, error)
+      end
+
       it "can set a rel, overriding a passed value" do
         helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow")
         helper.set_rel("noreferrer")
@@ -412,6 +424,12 @@
         helper.add_rel("noreferrer")
         expect(helper.all_attributes[:rel]).to eql("nofollow noreferrer")
       end
+
+      it "can add multiple rels to an existing rel" do
+        helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(rel: "nofollow")
+        helper.add_rel("noreferrer external")
+        expect(helper.all_attributes[:rel]).to eql("nofollow noreferrer external")
+      end
     end
 
     describe "margins" do