Extract flash warnings to presenter

app/controllers/application_controller.rb

@@ -8,6 +8,10 @@ def deny_user_access
     redirect_to new_session_path
   end
 
+  def flash_presenter
+    @flash_presenter ||= FlashPresenter.new(flash)
+  end
+
   def nav_presenter
     @nav_presenter ||= NavPresenter.new(viewing_user: viewing_user)
   end
@@ -16,6 +20,5 @@ def viewing_user
     current_user || NullUser.new
   end
 
-  helper_method :nav_presenter
-  helper_method :viewing_user
+  helper_method :flash_presenter, :nav_presenter, :viewing_user
 end

app/presenters/flash_presenter.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+class FlashPresenter
+  include ActionView::Helpers
+
+  def initialize(flash)
+    @flash = flash
+  end
+
+  def html
+    content_tag(:article, inner_html, class: 'message is-warning').html_safe
+  end
+
+  private
+
+  attr_reader :flash
+
+  def body
+    content_tag(:div, flash.alert, class: 'message-body')
+  end
+
+  def delete_button
+    content_tag(:button, '', class: 'delete', 'aria-label': 'delete')
+  end
+
+  def header
+    content_tag(:div, header_interior, class: 'message-header')
+  end
+
+  def header_interior
+    [warning, delete_button].join.html_safe
+  end
+
+  def inner_html
+    [header, body].join.html_safe
+  end
+
+  def warning
+    content_tag(:p, 'Warning')
+  end
+end

app/views/layouts/application.html.erb

@@ -23,16 +23,9 @@
     <%= nav_presenter.html %>
     <div class='container'>
       <% if flash.alert.present? %>
-        <article class="message is-warning">
-          <div class="message-header">
-            <p>Warning</p>
-            <button class="delete" aria-label="delete"></button>
-          </div>
-          <div class="message-body">
-            <%= flash.alert %>
-          </div>
-        </article>
+          <%= flash_presenter.html %>
       <% end %>
+      
       <%= yield %>
     </div>
     <footer class="footer">

spec/presenters/flash_presenter_spec.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe FlashPresenter do
+  describe '#html' do
+    let(:html) { described_class.new(flash).html }
+    let(:flash) { double(alert: 'Danger Will Robinson') }
+
+    it 'displays the correct HTML' do
+      expect(html).to include('<article class="message is-warning">')
+      expect(html).to include('<div class="message-header">')
+      expect(html).to include('<p>Warning</p>')
+      expect(html).to include('<button class="delete" aria-label="delete"></button>')
+      expect(html).to include('<div class="message-body">')
+      expect(html).to include('Danger Will Robinson')
+      expect(html).to include('</div>')
+      expect(html).to include('</article>')
+    end
+  end
+end