Add tests for preferences_helper

app/helpers/preferences_helper.rb

@@ -50,10 +50,6 @@ module PreferencesHelper
     ]
   end
 
-  def default_first_day_of_week
-    first_day_of_week_choices.rassoc(Gitlab::CurrentSettings.first_day_of_week).first
-  end
-
   def first_day_of_week_choices_with_default
     first_day_of_week_choices.unshift([_('System default (%{default})') % { default: default_first_day_of_week }, nil])
   end
@@ -81,4 +77,8 @@ module PreferencesHelper
   def excluded_dashboard_choices
     ['operations']
   end
+
+  def default_first_day_of_week
+    first_day_of_week_choices.rassoc(Gitlab::CurrentSettings.first_day_of_week).first
+  end
 end

spec/helpers/preferences_helper_spec.rb

@@ -35,6 +35,30 @@ describe PreferencesHelper do
     end
   end
 
+  describe '#first_day_of_week_choices' do
+    it 'returns Sunday and Monday as choices' do
+      expect(helper.first_day_of_week_choices).to eq [
+        ['Sunday', 0],
+        ['Monday', 1]
+      ]
+    end
+  end
+
+  describe '#first_day_of_week_choices_with_default' do
+    it 'returns choices including system default' do
+      expect(helper.first_day_of_week_choices_with_default).to eq [
+        ['System default (Sunday)', nil], ['Sunday', 0], ['Monday', 1]
+      ]
+    end
+
+    it 'returns choices including system default set to Monday' do
+      stub_application_setting(first_day_of_week: 1)
+      expect(helper.first_day_of_week_choices_with_default).to eq [
+        ['System default (Monday)', nil], ['Sunday', 0], ['Monday', 1]
+      ]
+    end
+  end
+
   describe '#user_application_theme' do
     context 'with a user' do
       it "returns user's theme's css_class" do