Refactor zones

- Rename "zonefile_setting" to "zone"
- Remove version

#475

spec/views/admin/dns/zones/index.html.erb_spec.rb

@@ -0,0 +1,40 @@
+require 'rails_helper'
+
+RSpec.describe 'admin/dns/zones/index' do
+  let(:zones) { [] }
+
+  before :example do
+    assign(:zones, zones)
+    stub_template '_zone' => 'zone-row'
+  end
+
+  it 'has title' do
+    render
+    expect(rendered).to have_text(t('admin.dns.zones.index.title'))
+  end
+
+  context 'when zones are present' do
+    let(:zones) { [build_stubbed(:zone)] }
+
+    it 'has zone row' do
+      render
+      expect(rendered).to have_text('zone-row')
+    end
+
+    it 'has no :not_found message' do
+      render
+      expect(rendered).to_not have_text(not_found_message)
+    end
+  end
+
+  context 'when zones are absent' do
+    it 'has :not_found message' do
+      render
+      expect(rendered).to have_text(not_found_message)
+    end
+  end
+
+  def not_found_message
+    t('admin.dns.zones.index.not_found')
+  end
+end