Only offer translation for supported languages (#23879)

2 files changed, 171 insertions, 0 deletions

diff --git a/spec/lib/translation_service/deepl_spec.rb b/spec/lib/translation_service/deepl_spec.rb
new file mode 100644
index 000000000..aa2473186
--- /dev/null
+++ b/spec/lib/translation_service/deepl_spec.rb
@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe TranslationService::DeepL do
+  subject(:service) { described_class.new(plan, 'my-api-key') }
+
+  let(:plan) { 'advanced' }
+
+  before do
+    stub_request(:get, 'https://api.deepl.com/v2/languages?type=source').to_return(
+      body: '[{"language":"EN","name":"English"},{"language":"UK","name":"Ukrainian"}]'
+    )
+    stub_request(:get, 'https://api.deepl.com/v2/languages?type=target').to_return(
+      body: '[{"language":"EN-GB","name":"English (British)"},{"language":"ZH","name":"Chinese"}]'
+    )
+  end
+
+  describe '#supported?' do
+    it 'supports included languages as source and target languages' do
+      expect(service.supported?('uk', 'en')).to be true
+    end
+
+    it 'supports auto-detecting source language' do
+      expect(service.supported?(nil, 'en')).to be true
+    end
+
+    it 'supports "en" and "pt" as target languages though not included in language list' do
+      expect(service.supported?('uk', 'en')).to be true
+      expect(service.supported?('uk', 'pt')).to be true
+    end
+
+    it 'does not support non-included language as target language' do
+      expect(service.supported?('uk', 'nl')).to be false
+    end
+
+    it 'does not support non-included language as source language' do
+      expect(service.supported?('da', 'en')).to be false
+    end
+  end
+
+  describe '#translate' do
+    it 'returns translation with specified source language' do
+      stub_request(:post, 'https://api.deepl.com/v2/translate')
+        .with(body: 'text=Hasta+la+vista&source_lang=ES&target_lang=en&tag_handling=html')
+        .to_return(body: '{"translations":[{"detected_source_language":"ES","text":"See you soon"}]}')
+
+      translation = service.translate('Hasta la vista', 'es', 'en')
+      expect(translation.detected_source_language).to eq 'es'
+      expect(translation.provider).to eq 'DeepL.com'
+      expect(translation.text).to eq 'See you soon'
+    end
+
+    it 'returns translation with auto-detected source language' do
+      stub_request(:post, 'https://api.deepl.com/v2/translate')
+        .with(body: 'text=Guten+Tag&source_lang&target_lang=en&tag_handling=html')
+        .to_return(body: '{"translations":[{"detected_source_language":"DE","text":"Good Morning"}]}')
+
+      translation = service.translate('Guten Tag', nil, 'en')
+      expect(translation.detected_source_language).to eq 'de'
+      expect(translation.provider).to eq 'DeepL.com'
+      expect(translation.text).to eq 'Good Morning'
+    end
+  end
+
+  describe '#languages?' do
+    it 'returns source languages' do
+      expect(service.send(:languages, 'source')).to eq ['en', 'uk', nil]
+    end
+
+    it 'returns target languages' do
+      expect(service.send(:languages, 'target')).to eq %w(en-gb zh en pt)
+    end
+  end
+
+  describe '#request' do
+    before do
+      stub_request(:any, //)
+      # rubocop:disable Lint/EmptyBlock
+      service.send(:request, :get, '/v2/languages') { |res| }
+      # rubocop:enable Lint/EmptyBlock
+    end
+
+    it 'uses paid plan base URL' do
+      expect(a_request(:get, 'https://api.deepl.com/v2/languages')).to have_been_made.once
+    end
+
+    context 'with free plan' do
+      let(:plan) { 'free' }
+
+      it 'uses free plan base URL' do
+        expect(a_request(:get, 'https://api-free.deepl.com/v2/languages')).to have_been_made.once
+      end
+    end
+
+    it 'sends API key' do
+      expect(a_request(:get, 'https://api.deepl.com/v2/languages').with(headers: { Authorization: 'DeepL-Auth-Key my-api-key' })).to have_been_made.once
+    end
+  end
+end
diff --git a/spec/lib/translation_service/libre_translate_spec.rb b/spec/lib/translation_service/libre_translate_spec.rb
new file mode 100644
index 000000000..a6cb01884
--- /dev/null
+++ b/spec/lib/translation_service/libre_translate_spec.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe TranslationService::LibreTranslate do
+  subject(:service) { described_class.new('https://libretranslate.example.com', 'my-api-key') }
+
+  before do
+    stub_request(:get, 'https://libretranslate.example.com/languages').to_return(
+      body: '[{"code": "en","name": "English","targets": ["de","es"]},{"code": "da","name": "Danish","targets": ["en","de"]}]'
+    )
+  end
+
+  describe '#supported?' do
+    it 'supports included language pair' do
+      expect(service.supported?('en', 'de')).to be true
+    end
+
+    it 'does not support reversed language pair' do
+      expect(service.supported?('de', 'en')).to be false
+    end
+
+    it 'supports auto-detecting source language' do
+      expect(service.supported?(nil, 'de')).to be true
+    end
+
+    it 'does not support auto-detecting for unsupported target language' do
+      expect(service.supported?(nil, 'pt')).to be false
+    end
+  end
+
+  describe '#languages' do
+    subject(:languages) { service.send(:languages) }
+
+    it 'includes supported source languages' do
+      expect(languages.keys).to eq ['en', 'da', nil]
+    end
+
+    it 'includes supported target languages for source language' do
+      expect(languages['en']).to eq %w(de es)
+    end
+
+    it 'includes supported target languages for auto-detected language' do
+      expect(languages[nil]).to eq %w(de es en)
+    end
+  end
+
+  describe '#translate' do
+    it 'returns translation with specified source language' do
+      stub_request(:post, 'https://libretranslate.example.com/translate')
+        .with(body: '{"q":"Hasta la vista","source":"es","target":"en","format":"html","api_key":"my-api-key"}')
+        .to_return(body: '{"translatedText": "See you"}')
+
+      translation = service.translate('Hasta la vista', 'es', 'en')
+      expect(translation.detected_source_language).to eq 'es'
+      expect(translation.provider).to eq 'LibreTranslate'
+      expect(translation.text).to eq 'See you'
+    end
+
+    it 'returns translation with auto-detected source language' do
+      stub_request(:post, 'https://libretranslate.example.com/translate')
+        .with(body: '{"q":"Guten Morgen","source":"auto","target":"en","format":"html","api_key":"my-api-key"}')
+        .to_return(body: '{"detectedLanguage":{"confidence":92,"language":"de"},"translatedText":"Good morning"}')
+
+      translation = service.translate('Guten Morgen', nil, 'en')
+      expect(translation.detected_source_language).to be_nil
+      expect(translation.provider).to eq 'LibreTranslate'
+      expect(translation.text).to eq 'Good morning'
+    end
+  end
+end