Maintenance: Add test for Translation.sync with all active locales.

Gemfile.lock

@@ -172,7 +172,7 @@ GEM
     erubi (1.10.0)
     eventmachine (1.2.7)
     execjs (2.8.1)
-    factory_bot (6.2.0)
+    factory_bot (6.2.1)
       activesupport (>= 5.0.0)
     factory_bot_rails (6.2.0)
       factory_bot (~> 6.2.0)
@@ -508,7 +508,7 @@ GEM
     shoulda-matchers (5.1.0)
       activesupport (>= 5.2.0)
     simple_oauth (0.3.1)
-    simple_po_parser (1.1.5)
+    simple_po_parser (1.1.6)
     slack-notifier (2.4.0)
     slack-ruby-client (1.0.0)
       faraday (>= 1.0)

spec/models/translation/translation_synchronizes_from_po_spec.rb

@@ -189,9 +189,10 @@ RSpec.describe Translation do
     end
   end
 
-  context 'when synchronizing strings for all locales' do
+  context 'when synchronizing strings for CI locales' do
 
-    before do
+    # Tests are slow, so use before :all to save time.
+    before :all do # rubocop:disable RSpec/BeforeAfterAll
       # Simulate additional entries
       File.write(Rails.root.join('i18n/testaddon.de-de.po'), <<~CUSTOM_PO)
         msgid "custom-string-translated"
@@ -213,7 +214,7 @@ RSpec.describe Translation do
       described_class.sync
     end
 
-    after do
+    after :all do # rubocop:disable RSpec/BeforeAfterAll
       FileUtils.remove(Rails.root.join('i18n/testaddon.de-de.po'))
     end
 
@@ -250,4 +251,17 @@ RSpec.describe Translation do
     end
   end
 
+  # Make sure that translation imports work really for all locales.
+  context 'when synchronizing strings for all locales' do
+    before do
+      # Only 'en-us' and 'de-de' are returned in test env - override.
+      allow(Locale).to receive(:to_sync).and_return(Locale.where(active: true))
+      described_class.sync
+    end
+
+    it 'imports without error and finds Chinese entries' do
+      expect(described_class.where(locale: 'zh-cn').count).to be > 500
+    end
+  end
+
 end