Add link to permission error page

If the user is a GDS Admin and lands on the permission error page then
render a link to edit the access of the edition (if it's an edition that
has caused the access error).

Author: patrickpatrickpatrick

app/views/admin/errors/forbidden.html.erb

@@ -5,8 +5,16 @@
 <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>
-
+    <% if @edition && can?(:perform_administrative_tasks, Edition) %>
+      <p class="govuk-body">
+        <a href="<%= edit_access_limited_admin_edition_path(@edition) %>" class="govuk-link">
+          As an administrator, you can update the access permissions of the page.
+        </a>
+      </p>
+      <p class="govuk-body">Alternatively, if you need to:</p>
+    <% else %>
+      <p class="govuk-body">If you need to:</p>
+    <% end %>
     <%= render "govuk_publishing_components/components/list", {
       visible_counters: true,
       items: [

features/admin-limit-access-editions.feature

@@ -0,0 +1,17 @@
+Feature: Viewing most recent editions in admin
+
+  Scenario: Viewing a current edition that has since been access limited as an editor
+    Given I am an editor
+    Given a published document "Road accidents" exists
+    When someone else creates a new edition of the published document "Road accidents" and limits access to members of "Department of Secrecy"
+    And I view the current edition of document "Road accidents"
+    Then I am told I do not have permissions to access this page
+    And I should not see a link to edit the access
+
+  Scenario: Viewing a current edition that has since been access limited as a GDS admin
+    Given I am a GDS admin
+    Given a published document "Road accidents" exists
+    When someone else creates a new edition of the published document "Road accidents" and limits access to members of "Department of Secrecy"
+    And I view the current edition of document "Road accidents"
+    Then I am told I do not have permissions to access this page
+    And I should see a link to edit the access

features/step_definitions/admin_limit_access_steps.rb

@@ -0,0 +1,16 @@
+When(/^I view the current edition of document "([^"]*)"$/) do |title|
+  @edition = Edition.find_by(title:).document.editions.last
+  visit admin_edition_path(@edition)
+end
+
+Then(/^I am told I do not have permissions to access this page/) do
+  expect(page).to have_content "You do not have permission to access this page."
+end
+
+Then(/^I should not see a link to edit the access/) do
+  expect(page).not_to have_link("As an administrator, you can update the access permissions of the page.", href: edit_access_limited_admin_edition_path(@edition))
+end
+
+Then(/^I should see a link to edit the access/) do
+  expect(page).to have_link("As an administrator, you can update the access permissions of the page.", href: edit_access_limited_admin_edition_path(@edition))
+end

features/step_definitions/edition_update_slug_steps.rb

@@ -18,7 +18,3 @@
   visit admin_edition_path(Publication.find_by(title:))
   expect(page).to have_link "Preview on website (opens in new tab)", href: "https://draft-origin.test.gov.uk/government/publications/#{new_slug}"
 end
-
-Then(/^I am told I do not have permissions to access this page/) do
-  expect(page).to have_content "You do not have permission to access this page."
-end