Show flash notice

app/controllers/users_controller.rb

@@ -56,13 +56,14 @@ class UsersController < ApplicationController
         redirect_to account_path
       else
         user_name = @user.name&.possessive || @user.email.possessive
-        case user_params[:active]
-        when "false"
+        if user_params[:active] == "false"
           @user.update!(confirmed_at: nil, sign_in_count: 0, initial_confirmation_sent: false)
           flash[:notice] = I18n.t("devise.activation.deactivated", user_name:)
-        when "true"
+        elsif user_params[:active] == "true"
           @user.send_confirmation_instructions
           flash[:notice] = I18n.t("devise.activation.reactivated", user_name:)
+        elsif user_params.key?("email") && FeatureToggle.new_email_journey?
+          flash[:notice] = I18n.t("devise.email.updated", email: @user.unconfirmed_email)
         end
         redirect_to user_path(@user)
       end

config/locales/en.yml

@@ -684,6 +684,8 @@ Make sure these answers are correct."
       hint_text: "This is more than 5 times the income, which is higher than we would expect."
 
   devise:
+    email:
+      updated: An email has been sent to %{email} to confirm this change.
     two_factor_authentication:
       success: "Two-factor authentication successful"
       attempt_failed: "Attempt failed"

spec/requests/users_controller_spec.rb

@@ -1730,6 +1730,12 @@ RSpec.describe UsersController, type: :request do
                   allow(FeatureToggle).to receive(:new_email_journey?).and_return(true)
                 end
 
+                it "shows flash notice" do
+                  patch("/users/#{other_user.id}", headers:, params:)
+
+                  expect(flash[:notice]).to eq("An email has been sent to #{new_email} to confirm this change.")
+                end
+
                 it "sends a new flow emails" do
                   expect(notify_client).to receive(:send_email).with(
                     email_address: other_user.email,