#428

backend/spec/requests/locale_resolution_spec.rb

@@ -0,0 +1,54 @@
+require 'rails_helper'
+
+RSpec.describe 'API locale resolution', type: :request do
+  let!(:tag) { create(:tag, primary_name: '日本語正本') }
+
+  it 'defaults an omitted locale to Japanese' do
+    get "/tags/#{ tag.id }"
+
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('name')).to eq('日本語正本')
+  end
+
+  it 'accepts an explicitly requested active Japanese locale' do
+    get "/tags/#{ tag.id }", params: { locale: 'ja' }
+
+    expect(response).to have_http_status(:ok)
+    expect(json.fetch('name')).to eq('日本語正本')
+  end
+
+  ['', 'en', 'ain', 'Jpan', 'JA', 'unknown', ['ja']].each do |code|
+    it "rejects invalid locale #{ code.inspect } instead of defaulting to Japanese" do
+      get "/tags/#{ tag.id }", params: { locale: code }
+
+      expect(response).to have_http_status(:not_found)
+      expect(response.body).not_to include('日本語正本')
+    end
+  end
+
+  it 'rejects a supported locale that has not been registered' do
+    get "/tags/#{ tag.id }", params: { locale: 'ain-Kana' }
+
+    expect(response).to have_http_status(:not_found)
+  end
+
+  it 'rejects an inactive locale' do
+    Locale.nipponese.update!(deprecated_at: Time.current)
+
+    get "/tags/#{ tag.id }", params: { locale: 'ja' }
+
+    expect(response).to have_http_status(:not_found)
+  end
+
+  it 'does not write posts or tag names under an invalid locale' do
+    sign_in_as(create_member_user!)
+
+    expect do
+      post '/posts', params: {
+          locale: 'en', title: 'invalid locale', url: 'https://example.com/invalid-locale',
+          tags: 'unwritten_tag' }
+    end.to change(Post, :count).by(0).and change(TagName, :count).by(0)
+
+    expect(response).to have_http_status(:not_found)
+  end
+end