I18n pluralization errors (mastodon#24963)

Gemfile.lock

@@ -329,7 +329,7 @@ GEM
     httplog (1.6.2)
       rack (>= 2.0)
       rainbow (>= 2.0.0)
-    i18n (1.12.0)
+    i18n (1.13.0)
       concurrent-ruby (~> 1.0)
     i18n-tasks (1.0.12)
       activesupport (>= 4.0.2)

spec/views/shared/_error_messages.html.haml_spec.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'shared/_error_messages.html.haml' do
+  let(:status) { Status.new }
+
+  before { status.errors.add :base, :invalid }
+
+  context 'with a locale that has `one` and `other` plural values' do
+    around do |example|
+      I18n.with_locale(:en) do
+        example.run
+      end
+    end
+
+    it 'renders the view with one error' do
+      render partial: 'shared/error_messages', locals: { object: status }
+
+      expect(rendered).to match(/is invalid/)
+    end
+  end
+
+  context 'with a locale that has only `other` plural value' do
+    around do |example|
+      I18n.with_locale(:my) do
+        example.run
+      end
+    end
+
+    it 'renders the view with one error' do
+      render partial: 'shared/error_messages', locals: { object: status }
+
+      expect(rendered).to match(/is invalid/)
+    end
+  end
+end