Add flash banner spec and functionality

app/controllers/users/passwords_controller.rb

@@ -1,6 +1,7 @@
 class Users::PasswordsController < Devise::PasswordsController
   def reset_confirmation
     @email = params["email"]
+    flash[:notice] = "Reset password instructions have been sent to #{@email}"
     render "devise/confirmations/reset"
   end
 

spec/requests/users/passwords_controller_spec.rb

@@ -29,5 +29,11 @@ RSpec.describe Users::PasswordsController, type: :request do
       follow_redirect!
       expect(response.body).to match(/Check your email/)
     end
+
+    it "shows a flash banner" do
+      post "/users/password", params: params
+      follow_redirect!
+      expect(flash[:notice]).to be_present
+    end
   end
 end