Fix/i18n locale issue (#11197)

* Revert "Fix Duplicate Locales Coming From spree_i18n (#10871)"

* Map to_sym so unique works.

* Fix test.

* Hard code values for result.

* Static code expected results.

core/lib/spree/i18n.rb

@@ -18,7 +18,12 @@ def translate(key, options = {})
 
     def available_locales
       locales_from_i18n = I18n.available_locales
-      locales = [Rails.application.config.i18n.default_locale, I18n.locale, :en]
+      locales =
+        if defined?(SpreeI18n)
+          (SpreeI18n::Locale.all << :en).map(&:to_sym)
+        else
+          [Rails.application.config.i18n.default_locale, I18n.locale, :en]
+        end
 
       (locales + locales_from_i18n).uniq.compact
     end

core/spec/lib/i18n_spec.rb

@@ -19,12 +19,35 @@
   end
 
   describe '#available_locales' do
-    it 'returns locales defined in Spree and all other installed gems' do
-      locales = Spree.available_locales
+    context 'when SpreeI18n is defined' do
+      before do
+        class_double('SpreeI18n').
+          as_stubbed_const(transfer_nested_constants: true)
+        class_double('SpreeI18n::Locale', all: ['en',:en, :de, :nl]).as_stubbed_const(transfer_nested_constants: true)
+      end
+
+      it 'returns all locales from the SpreeI18n' do
+        locales = Spree.available_locales
+        expected_locales = [:en, :de, :nl, :ar, :az, :bg, :ca, :cs, :da, :el, :es, :fa, :fi, :fr, :hu, :id, :it, :ja, :"pt-BR", :ro, :ru, :sk, :tr, :"zh-CN", :"zh-TW", :pl, :uk, :vi]
+
+        expect(locales).to eq expected_locales
+      end
+
+      it 'returns an array with the string "en" removed' do
+        locales = Spree.available_locales
 
-      expected_locales = ([Rails.application.config.i18n.default_locale, I18n.locale, :en] + I18n.available_locales).uniq.compact
+        expect(locales).not_to include('en')
+      end
+    end
+
+    context 'when SpreeI18n is not defined' do
+      it 'returns just default locales' do
+        locales = Spree.available_locales
 
-      expect(locales).to eq expected_locales
+        expected_locales = [:en, :ar, :az, :bg, :ca, :cs, :da, :de, :el, :es, :fa, :fi, :fr, :hu, :id, :it, :ja, :nl, :"pt-BR", :ro, :ru, :sk, :tr, :"zh-CN", :"zh-TW", :pl, :uk, :vi]
+
+        expect(locales).to eq expected_locales
+      end
     end
   end