Avoid stubbing in the banner integration test

Integration tests shouldn't use stubbing at all. Instead, create
real files on the filesystem. This change involves making the path
to the banner templates configurable, with the default being in
"app/views/notifications".

lib/notification_file_lookup.rb

@@ -1,4 +1,8 @@
 class NotificationFileLookup
+  def initialize(banner_file_location = "#{Rails.root}/app/views/notifications")
+    @banner_file_location = banner_file_location
+  end
+
   def banner
     @banner_file ||= identify_banner_file
   end
@@ -10,8 +14,8 @@ def banner=(file)
   private
 
   def identify_banner_file
-    red = File.read("#{Rails.root}/app/views/notifications/banner_red.erb").strip
-    green = File.read("#{Rails.root}/app/views/notifications/banner_green.erb").strip
+    red = File.read(File.join(@banner_file_location, "banner_red.erb")).strip
+    green = File.read(File.join(@banner_file_location, "banner_green.erb")).strip
 
     case
     when red.present?

test/integration/notifications_test.rb

@@ -20,14 +20,16 @@ class NotificationsTest < ActionDispatch::IntegrationTest
   end
 
   context "banner notifications" do
+    teardown do
+      clean_up_test_files
+    end
+
     context "given view files are empty" do
       setup do
-        File.stubs(:read).with("#{Rails.root}/app/views/notifications/banner_green.erb")
-          .returns('')
-        File.stubs(:read).with("#{Rails.root}/app/views/notifications/banner_red.erb")
-          .returns('')
+        create_test_file(filename: "banner_green.erb", content: '')
+        create_test_file(filename: "banner_red.erb", content: '')
 
-        Static.banner = NotificationFileLookup.new.banner
+        Static.banner = NotificationFileLookup.new(location_of_test_files).banner
       end
 
       should "not show a banner notification on the page" do
@@ -38,12 +40,10 @@ class NotificationsTest < ActionDispatch::IntegrationTest
 
     context "given view files are present for a green notification" do
       setup do
-        File.stubs(:read).with("#{Rails.root}/app/views/notifications/banner_green.erb")
-          .returns('<p>Everything is fine</p>')
-        File.stubs(:read).with("#{Rails.root}/app/views/notifications/banner_red.erb")
-          .returns('')
+        create_test_file(filename: "banner_green.erb", content: '<p>Everything is fine</p>')
+        create_test_file(filename: "banner_red.erb", content: '')
 
-        Static.banner = NotificationFileLookup.new.banner
+        Static.banner = NotificationFileLookup.new(location_of_test_files).banner
       end
 
       should "show a banner notification on the page" do
@@ -55,12 +55,10 @@ class NotificationsTest < ActionDispatch::IntegrationTest
 
     context "given view files are present for a red notification" do
       setup do
-        File.stubs(:read).with("#{Rails.root}/app/views/notifications/banner_green.erb")
-          .returns('')
-        File.stubs(:read).with("#{Rails.root}/app/views/notifications/banner_red.erb")
-          .returns('<p>Everything is not fine</p>')
+        create_test_file(filename: "banner_green.erb", content: '')
+        create_test_file(filename: "banner_red.erb", content: '<p>Everything is not fine</p>')
 
-        Static.banner = NotificationFileLookup.new.banner
+        Static.banner = NotificationFileLookup.new(location_of_test_files).banner
       end
 
       should "show a banner notification on the page" do

test/test_helper.rb

@@ -6,3 +6,19 @@
 require 'test/unit'
 require 'rails/test_help'
 require 'mocha/mini_test'
+
+class ActiveSupport::TestCase
+  def create_test_file(filename:, content:)
+    FileUtils.mkdir_p location_of_test_files
+    full_path = File.join(location_of_test_files, filename)
+    File.open(full_path, "w") {|f| f << content }
+  end
+
+  def location_of_test_files
+    Rails.root.join("tmp", "test")
+  end
+
+  def clean_up_test_files
+    FileUtils.rm_r location_of_test_files
+  end
+end