OTWO-7292 Handle missing flag images for Stacks (#1796)

app/helpers/stacks_helper.rb

@@ -14,8 +14,17 @@ def stack_similar_project_list(projects)
   end
 
   def stack_country_flag(code)
-    return '' unless code && code.size == 2
+    img_relative_path = "flags/#{code.to_s.downcase}.gif"
+    return '' unless asset_exists?(img_relative_path)
 
-    haml_tag 'img', src: asset_url("flags/#{code.downcase}.gif")
+    haml_tag 'img', src: asset_url(img_relative_path)
+  end
+
+  def asset_exists?(path)
+    if Rails.configuration.assets.compile
+      Rails.application.precompiled_assets.include? path
+    else
+      Rails.application.assets_manifest.assets[path].present?
+    end
   end
 end

test/helpers/stacks_helper_test.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class StacksHelperTest < ActionView::TestCase
+  include StacksHelper
+
+  describe 'stack_country_flag' do
+    it 'must return an html with the flag image' do
+      dummy_html = '<img/>'
+      expects(:haml_tag).once.returns(dummy_html)
+
+      _(stack_country_flag('Us')).must_equal dummy_html
+    end
+
+    it 'must handle invalid country codes' do
+      _(stack_country_flag('invalid')).must_be :blank?
+    end
+
+    it 'must handle blank codes' do
+      _(stack_country_flag(nil)).must_be :blank?
+    end
+
+    it 'must handle missing flag images' do
+      _(stack_country_flag('uk')).must_be :blank?
+    end
+
+    it 'must use the assets_manifest when assets are not compiled' do
+      Rails.configuration.assets.stubs(:compile).returns(false)
+      Rails.application.assets_manifest.expects(:assets).once.returns({})
+
+      _(stack_country_flag('')).must_be :blank?
+    end
+  end
+end