Update ErrorsController to support ContentBlockManager

This adds override templates to ContentBlockManager for the error pages,
if the request path starts with the ContentBlockManager router prefix,
we prepend the view path, so the overridden views are picked up.

Additionally, we also need to do this for the `forbidden!` helper, as
there isn’t a specific error we can raise that will result in a
`forbidden` error

app/controllers/admin/base_controller.rb

@@ -49,6 +49,7 @@ def product_name
 private
 
   def forbidden!
+    prepend_view_path Rails.root.join("lib/engines/content_block_manager/app/views") if request.path.start_with?(ContentBlockManager.router_prefix)
     render "admin/errors/forbidden", status: :forbidden
   end
 

app/controllers/admin/errors_controller.rb

@@ -1,4 +1,6 @@
 class Admin::ErrorsController < Admin::BaseController
+  before_action :prepend_content_block_manager_view_path, if: -> { request.path.start_with?(ContentBlockManager.router_prefix) }
+
   def bad_request
     render(status: :bad_request)
   end
@@ -18,4 +20,10 @@ def unprocessable_entity
   def internal_server_error
     render(status: :internal_server_error)
   end
+
+private
+
+  def prepend_content_block_manager_view_path
+    prepend_view_path Rails.root.join("lib/engines/content_block_manager/app/views")
+  end
 end

lib/engines/content_block_manager/app/views/admin/errors/bad_request.html.erb

@@ -0,0 +1,10 @@
+<% content_for :product_name, ContentBlockManager.product_name %>
+<% content_for :page_title, "Something went wrong" %>
+<% content_for :title, "Something went wrong" %>
+<% content_for :title_margin_bottom, 6 %>
+
+<div class="govuk-grid-row govuk-!-margin-bottom-0">
+  <div class="govuk-grid-column-two-thirds">
+    <p class="govuk-body">Please try again by selecting the browser&rsquo;s back button or <%= link_to "raise a support request", ContentBlockManager.support_url, class: "govuk-link govuk-link--no-visited-state" %></p>
+  </div>
+</div>

lib/engines/content_block_manager/app/views/admin/errors/down_for_maintenance.html.erb

@@ -0,0 +1,10 @@
+<% content_for :product_name, ContentBlockManager.product_name %>
+<% content_for :page_title, "Down for maintenance" %>
+<% content_for :title, "Down for maintenance" %>
+<% content_for :title_margin_bottom, 6 %>
+
+<div class="govuk-grid-row govuk-!-margin-bottom-0">
+  <div class="govuk-grid-column-two-thirds">
+    <p class="govuk-body"><%= ContentBlockManager.product_name %> is currently down for maintenance. We'll be back soon.</p>
+  </div>
+</div>

lib/engines/content_block_manager/app/views/admin/errors/forbidden.html.erb

@@ -0,0 +1,19 @@
+<% content_for :product_name, ContentBlockManager.product_name %>
+<% content_for :page_title, "Permissions error" %>
+<% content_for :title, "Permissions error" %>
+<% content_for :title_margin_bottom, 6 %>
+
+<div class="govuk-grid-row govuk-!-margin-bottom-0">
+  <div class="govuk-grid-column-two-thirds">
+    <p class="govuk-body">You do not have permission to access this page.</p>
+    <p class="govuk-body">If you need to:</p>
+
+    <%= render "govuk_publishing_components/components/list", {
+      visible_counters: true,
+      items: [
+        "view the page, request the preview link",
+        sanitize("edit the page, raise a #{link_to "support ticket", ContentBlockManager.support_url, class: "govuk-link govuk-link--no-visited-state"}"),
+      ],
+    } %>
+  </div>
+</div>

lib/engines/content_block_manager/app/views/admin/errors/internal_server_error.html.erb

@@ -0,0 +1,19 @@
+<% content_for :product_name, ContentBlockManager.product_name %>
+<% content_for :page_title, "Server error" %>
+<% content_for :title, "Server error" %>
+<% content_for :title_margin_bottom, 6 %>
+
+<div class="govuk-grid-row govuk-!-margin-bottom-0">
+  <div class="govuk-grid-column-two-thirds">
+    <p class="govuk-body">The error has been logged in our system.</p>
+    <p class="govuk-body">You can also raise a <a href="<%= ContentBlockManager.support_url %>" class="govuk-link">support ticket</a> with the following information:</p>
+
+    <%= render "govuk_publishing_components/components/list", {
+      visible_counters: true,
+      items: [
+        "the url of this page",
+        "the time of the error",
+      ],
+    } %>
+  </div>
+</div>

lib/engines/content_block_manager/app/views/admin/errors/not_found.html.erb

@@ -0,0 +1,11 @@
+<% content_for :product_name, ContentBlockManager.product_name %>
+<% content_for :page_title, "There is a mistake in the URL" %>
+<% content_for :title, "There is a mistake in the URL" %>
+<% content_for :title_margin_bottom, 6 %>
+
+<div class="govuk-grid-row govuk-!-margin-bottom-0">
+  <div class="govuk-grid-column-two-thirds">
+    <p class="govuk-body">If you typed the URL, check it is correct.</p>
+    <p class="govuk-body">If you pasted the URL, check you copied the entire address.</p>
+  </div>
+</div>

lib/engines/content_block_manager/app/views/admin/errors/unprocessable_entity.html.erb

@@ -0,0 +1,10 @@
+<% content_for :product_name, ContentBlockManager.product_name %>
+<% content_for :page_title, "Something went wrong" %>
+<% content_for :title, "Something went wrong" %>
+<% content_for :title_margin_bottom, 6 %>
+
+<div class="govuk-grid-row govuk-!-margin-bottom-0">
+  <div class="govuk-grid-column-two-thirds">
+    <p class="govuk-body">Please try again by selecting the browser&rsquo;s back button or <%= link_to "raise a support request", ContentBlockManager.support_url, class: "govuk-link govuk-link--no-visited-state" %>.</p>
+  </div>
+</div>

test/functional/admin/errors_controller_test.rb

@@ -1,32 +1,69 @@
 require "test_helper"
+require "capybara/rails"
 
 class Admin::ErrorsControllerTest < ActionDispatch::IntegrationTest
+  include Capybara::DSL
+  extend Minitest::Spec::DSL
+
   setup do
     login_as_admin
   end
 
-  test "should show the bad request page" do
-    get "/400"
-    assert_template :bad_request
-  end
+  ERROR_LOOKUPS = {
+    "400": :bad_request,
+    "403": :forbidden,
+    "404": :not_found,
+    "422": :unprocessable_entity,
+    "500": :internal_server_error,
+  }.freeze
 
-  test "should show the forbidden page" do
-    get "/403"
-    assert_template :forbidden
-  end
+  ERROR_LOOKUPS.each do |error_code, error|
+    it "should show the #{error} page" do
+      get "/#{error_code}"
 
-  test "should show the not found page" do
-    get "/404"
-    assert_template :not_found
-  end
+      assert_template error
+    end
+
+    it "should render the correct headers" do
+      get "/#{error_code}"
+
+      assert_select ".govuk-header__product-name", text: Whitehall.product_name
+      refute_select ".govuk-phase-banner__content__tag"
+    end
+
+    it "should render the product name in the title" do
+      get "/#{error_code}"
 
-  test "should show the unprocessable entity page" do
-    get "/422"
-    assert_template :unprocessable_entity
+      assert_select "title", text: /#{Whitehall.product_name}/
+    end
   end
 
-  test "should show the internal server error page" do
-    get "/500"
-    assert_template :internal_server_error
+  describe "when request comes from ContentBlockManager" do
+    before do
+      path = "some-path"
+      ActionDispatch::Request.any_instance.stubs(:path).returns(path)
+      path.stubs(:start_with?).with(ContentBlockManager.router_prefix).returns(true)
+    end
+
+    ERROR_LOOKUPS.each do |error_code, error|
+      it "should show the #{error} page" do
+        get "/#{error_code}"
+
+        assert_template error
+      end
+
+      it "should render the correct headers" do
+        get "/#{error_code}"
+
+        assert_select ".govuk-header__product-name", text: ContentBlockManager.product_name
+        assert_select ".govuk-phase-banner__content__tag", text: "Alpha"
+      end
+
+      it "should render the product name in the title" do
+        get "/#{error_code}"
+
+        assert_select "title", text: /#{ContentBlockManager.product_name}/
+      end
+    end
   end
 end