Add edge caching to shell (#5146) [deploy]

* Add edge caching to shell

* Add tests for shell

app/controllers/shell_controller.rb

@@ -1,13 +1,17 @@
 class ShellController < ApplicationController
+  before_action :set_cache_control_headers, only: %i[top bottom]
+
   layout false
 
   def top
     @shell = true
+    set_surrogate_key_header "shell-top"
     render partial: "top"
   end
 
   def bottom
     @shell = true
+    set_surrogate_key_header "shell-bottom"
     render partial: "bottom"
   end
 end

spec/requests/shells_spec.rb

@@ -0,0 +1,27 @@
+require "rails_helper"
+
+RSpec.describe "Shells", type: :request do
+  describe "GET /shell_top" do
+    it "renders file with proper text" do
+      get "/shell_top"
+      expect(response.body).to include("user-signed-in")
+    end
+
+    it "sends a surrogate key (for Fastly's user)" do
+      get "/shell_top"
+      expect(response.header["Surrogate-Key"]).to include("shell-top")
+    end
+  end
+
+  describe "GET /shell_bottom" do
+    it "renders file with proper text" do
+      get "/shell_bottom"
+      expect(response.body).to include("footer-container")
+    end
+
+    it "sends a surrogate key (for Fastly's user)" do
+      get "/shell_bottom"
+      expect(response.header["Surrogate-Key"]).to include("shell-bottom")
+    end
+  end
+end