Introduce candidate to wrong email address page

If a candidate tries to login with the candidate email address and they
have a one login email address that is different from the candidate
email address. We will not allow the user to login, with one login.

We will redirect the user to the wrong_email_address page.

Previously we would have redirected the user to 500 error page. This
page is intended to have more content helping the candidate to unstuck
themselves rather than contacting support

app/controllers/candidate_interface/errors_controller.rb

@@ -2,6 +2,7 @@ module CandidateInterface
   class ErrorsController < CandidateInterfaceController
     skip_before_action :verify_authenticity_token
     skip_before_action :authenticate_candidate!
+    allow_unauthenticated_access only: [:wrong_email_address]
 
     def account_locked
       render 'errors/account_locked', status: :forbidden, formats: :html
@@ -10,5 +11,9 @@ def account_locked
     def not_found
       render 'errors/not_found', status: :not_found, formats: :html
     end
+
+    def wrong_email_address
+      render 'errors/wrong_email_address_used_for_candidate', status: :forbidden, formats: :html
+    end
   end
 end

app/controllers/one_login_controller.rb

@@ -74,7 +74,7 @@ def sign_out
   def sign_out_complete
     if session[:session_error_id].present?
       reset_session
-      redirect_to internal_server_error_path
+      redirect_to candidate_interface_wrong_email_address_path
     else
       redirect_to candidate_interface_create_account_or_sign_in_path
     end

app/views/errors/wrong_email_address_used_for_candidate.html.erb

@@ -0,0 +1,14 @@
+<%= content_for :title, t('page_titles.there_is_a_problem') %>
+
+<div class="govuk-grid-row">
+  <div class="govuk-grid-column-two-thirds">
+    <h1 class="govuk-heading-l"><%= t('page_titles.there_is_a_problem') %></h1>
+    <p class="govuk-body">
+      You should use the email address you use for GOV.UK One Login to sign in to Apply for teacher training.
+    </p>
+    <p class="govuk-body">
+      If you have any questions, please email us at
+      <a class="govuk-link" href="mailto:[email protected]">[email protected]</a>
+    </p>
+  </div>
+</div>

config/locales/en.yml

@@ -102,6 +102,7 @@ en:
     get_your_details_back: Get your details back
     dismiss: Dismiss
   page_titles:
+    there_is_a_problem: There is a problem
     account_recovery: Enter the code we sent to %{email}
     account_recovery_resend_email: Enter the new code we sent to %{email}
     account_recovery_request: Get your account details back

config/routes/candidate.rb

@@ -608,6 +608,7 @@
   end
 
   get '/account-locked', to: 'errors#account_locked'
+  get '/wrong-email-address', to: 'errors#wrong_email_address'
 
   get '/about-the-teacher-training-application-process', to: 'guidance#index', as: :guidance
 

spec/requests/one_login_controller_spec.rb

@@ -199,7 +199,7 @@
           "One login session error, check session_error record #{SessionError.last.id}",
           level: :error,
         )
-        expect(response).to redirect_to(internal_server_error_path)
+        expect(response).to redirect_to(candidate_interface_wrong_email_address_path)
       end
     end