Add tests for translation helpers

spec/lib/govuk_publishing_components/components/shared_helper_spec.rb

@@ -1,5 +1,9 @@
 RSpec.describe GovukPublishingComponents::Presenters::SharedHelper do
   describe "Shared component helper" do
+    after(:each) do
+      I18n.locale = :en
+    end
+
     it "returns a default margin class" do
       shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
       margin_class = shared_helper.get_margin_bottom
@@ -52,5 +56,55 @@
         GovukPublishingComponents::Presenters::SharedHelper.new(classes: "js-okay not-cool-man")
       }.to raise_error(ArgumentError, "Passed classes must be prefixed with `js-`")
     end
+
+    it "returns nil if given locale is same as page locale" do
+      default_locale = I18n.locale
+      shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
+
+      expect(shared_helper.t_locale_check(default_locale)).to be nil
+    end
+
+    it "returns a locale if different to the page locale" do
+      locale = "ar"
+      shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
+
+      expect(shared_helper.t_locale_check(locale)).to eq locale
+    end
+
+    it "returns the language attribute if translation is not present" do
+      I18n.locale = :de
+
+      translation_key = "this.is.a.key.that.should.not.be.found.to.test.the.translation"
+      shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
+
+      expect(shared_helper.t_lang(translation_key)).to eq "lang=en"
+    end
+
+    it "returns no language attribute if translation is present" do
+      I18n.locale = :fr
+
+      translation_key = "components.contents_list.contents"
+      shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
+
+      expect(shared_helper.t_lang(translation_key)).to be nil
+    end
+
+    it "returns the locale if translation is not present" do
+      I18n.locale = :de
+
+      translation_key = "this.is.a.key.that.should.not.be.found.to.test.the.translation"
+      shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
+
+      expect(shared_helper.t_locale(translation_key)).to eq :en
+    end
+
+    it "returns no locale if translation is present and using default locale" do
+      I18n.locale = :fr
+
+      translation_key = "components.contents_list.contents"
+      shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new({})
+
+      expect(shared_helper.t_locale(translation_key)).to be :fr
+    end
   end
 end