Move form field partial to a component

This way it's easier to test; changing it will also be easier.

During my experiments I made a mistake which wasn't covered by the test
suite. We're adding a test for this case.

Note we're using `i18n_content` in the component instead of `content`
because there's already a `content` method provided by ViewComponent.

app/components/admin/site_customization/information_texts/form_field_component.html.erb

@@ -0,0 +1,9 @@
+<% globalize(locale) do %>
+  <%= hidden_field_tag "contents[content_#{i18n_content.key}][id]", i18n_content.key %>
+  <%= text_area_tag "contents[content_#{i18n_content.key}]values[value_#{locale}]",
+                    text || t(i18n_content.key, locale: locale),
+                    rows: 5,
+                    class: "js-globalize-attribute",
+                    style: site_customization_display_translation_style(locale),
+                    data:  { locale: locale } %>
+<% end %>

app/components/admin/site_customization/information_texts/form_field_component.rb

@@ -0,0 +1,19 @@
+class Admin::SiteCustomization::InformationTexts::FormFieldComponent < ApplicationComponent
+  attr_reader :i18n_content, :locale
+  delegate :globalize, :site_customization_display_translation_style, to: :helpers
+
+  def initialize(i18n_content, locale:)
+    @i18n_content = i18n_content
+    @locale = locale
+  end
+
+  private
+
+    def text
+      if i18n_content.present?
+        I18nContentTranslation.find_by(i18n_content_id: i18n_content.id, locale: locale)&.value
+      else
+        false
+      end
+    end
+end

app/helpers/site_customization_helper.rb

@@ -7,14 +7,6 @@ module SiteCustomizationHelper
     site_customization_enable_translation?(locale) ? "" : "display: none;"
   end
 
-  def translation_for_locale(content, locale)
-    if content.present?
-      I18nContentTranslation.find_by(i18n_content_id: content.id, locale: locale)&.value
-    else
-      false
-    end
-  end
-
   def information_texts_tabs
     [:basic, :debates, :community, :proposals, :polls, :layouts, :mailers, :management, :welcome, :machine_learning]
   end

app/views/admin/site_customization/information_texts/_form.html.erb

@@ -8,7 +8,7 @@
     <% group.each do |content| %>
       <b><%= content.key %></b>
       <% content.globalize_locales.each do |locale| %>
-        <%= render "form_field", content: content, locale: locale %>
+        <%= render Admin::SiteCustomization::InformationTexts::FormFieldComponent.new(content, locale: locale) %>
       <% end %>
     <% end %>
   <% end %>

app/views/admin/site_customization/information_texts/_form_field.html.erb

@@ -1,9 +0,0 @@
-<% globalize(locale) do %>
-  <%= hidden_field_tag "contents[content_#{content.key}][id]", content.key %>
-  <%= text_area_tag "contents[content_#{content.key}]values[value_#{locale}]",
-                    translation_for_locale(content, locale) || t(content.key, locale: locale),
-                    rows: 5,
-                    class: "js-globalize-attribute",
-                    style: site_customization_display_translation_style(locale),
-                    data:  { locale: locale } %>
-<% end %>

spec/components/admin/site_customization/information_texts/form_field_component_spec.rb

@@ -0,0 +1,14 @@
+require "rails_helper"
+
+describe Admin::SiteCustomization::InformationTexts::FormFieldComponent do
+  after { I18n.backend.reload! }
+
+  it "uses the I18n translation when the record exists without a database translation" do
+    I18n.backend.store_translations(:en, { testing: "It works!" })
+    content = I18nContent.create!(key: "testing")
+
+    render_inline Admin::SiteCustomization::InformationTexts::FormFieldComponent.new(content, locale: :en)
+
+    expect(page).to have_field with: "It works!"
+  end
+end