Load site default language ID into session unless the one in session …

app/controllers/concerns/alchemy/admin/current_language.rb

@@ -13,7 +13,11 @@ module CurrentLanguage
 
       def load_current_language
         @current_language = if session[:alchemy_language_id].present?
-          set_alchemy_language(session[:alchemy_language_id])
+          if Current.site.languages.where(id: session[:alchemy_language_id]).exists?
+            set_alchemy_language(session[:alchemy_language_id])
+          else
+            Current.site.default_language
+          end
         else
           Current.language
         end

lib/alchemy/test_support/current_language_shared_examples.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+RSpec.shared_examples_for "a controller that loads current language" do |args|
+  context "when session has current language id key" do
+    let!(:site_1) { create(:alchemy_site) }
+    let!(:site_1_default_language) { create :alchemy_language, site: site_1, default: true }
+    let!(:another_site_1_language) { create :alchemy_language, site: site_1, code: :de }
+    let(:site_2) { create :alchemy_site, host: "another.host", languages: [build(:alchemy_language, code: :en), build(:alchemy_language, code: :de)] }
+
+    before { session[:alchemy_language_id] = another_site_1_language.id }
+
+    context "when language ID in session is associated with the current site" do
+      it "sets @current_language" do
+        get :index, params: {site_id: site_1.id}
+        expect(assigns(:current_language)).to eq(another_site_1_language)
+      end
+    end
+
+    context "when language ID in session is not associated with the current site" do
+      it "sets @current_language to the current site default language" do
+        get :index, params: {site_id: site_2.id}
+        expect(assigns(:current_language)).to eq(site_2.default_language)
+      end
+
+      it "does not change the language ID in session" do
+        expect { get :index, params: {site_id: site_2.id} }.not_to change { session[:alchemy_language_id] }
+      end
+    end
+
+    context "when no language ID in session" do
+      before { session[:alchemy_language_id] = nil }
+
+      it "sets @current_language to language language" do
+        get :index, params: {site_id: site_2.id}
+        expect(assigns(:current_language)).to eq site_2.default_language
+      end
+    end
+
+    context "when no language to set" do
+      it "shows flash warning with redirect" do
+        Alchemy::Language.destroy_all
+        get :index, params: {site_id: site_1.id}
+        expect(flash[:warning]).to eq Alchemy.t("Please create a language first.")
+        expect(response).to redirect_to admin_languages_path
+      end
+    end
+  end
+end

spec/controllers/alchemy/admin/layoutpages_controller_spec.rb

@@ -10,6 +10,8 @@ module Alchemy
       authorize_user(:as_admin)
     end
 
+    it_behaves_like "a controller that loads current language"
+
     describe "#index" do
       context "with no language present" do
         it "redirects to the languages admin" do

spec/controllers/alchemy/admin/nodes_controller_spec.rb

@@ -10,6 +10,8 @@ module Alchemy
       authorize_user(:as_admin)
     end
 
+    it_behaves_like "a controller that loads current language"
+
     describe "#index" do
       context "if no language is present" do
         it "redirects to the language admin" do

spec/controllers/alchemy/admin/pages_controller_spec.rb

@@ -10,6 +10,8 @@
     authorize_user(:as_admin)
   end
 
+  it_behaves_like "a controller that loads current language"
+
   describe "#index" do
     let!(:page) { create(:alchemy_page) }
 

spec/rails_helper.rb

@@ -31,6 +31,7 @@
 require "alchemy/test_support/shared_contexts"
 require "alchemy/test_support/shared_link_tab_examples"
 require "alchemy/test_support/shared_uploader_examples"
+require "alchemy/test_support/current_language_shared_examples"
 
 require_relative "support/calculation_examples"
 require_relative "support/hint_examples"