use authentication_keys in flash message, instead of static ‘username’ (fix #3201)

config/locales/en.yml

@@ -9,10 +9,10 @@ en:
     failure:
       already_authenticated: "You are already signed in."
       inactive: "Your account is not activated yet."
-      invalid: "Invalid email or password."
+      invalid: "Invalid %{authentication_keys} or password."
       locked: "Your account is locked."
       last_attempt: "You have one more attempt before your account is locked."
-      not_found_in_database: "Invalid email or password."
+      not_found_in_database: "Invalid %{authentication_keys} or password."
       timeout: "Your session expired. Please sign in again to continue."
       unauthenticated: "You need to sign in or sign up before continuing."
       unconfirmed: "You have to confirm your email address before continuing."

lib/devise/failure_app.rb

@@ -78,6 +78,7 @@ module Devise
         options[:resource_name] = scope
         options[:scope] = "devise.failure"
         options[:default] = [message]
+        options[:authentication_keys] = Devise.authentication_keys.join(", ")
         options = i18n_options(options)
 
         I18n.t(:"#{scope}.#{message}", options)

test/integration/authenticatable_test.rb

@@ -580,7 +580,7 @@ class AuthenticationKeysTest < ActionDispatch::IntegrationTest
   test 'missing authentication keys cause authentication to abort' do
     swap Devise, authentication_keys: [:subdomain] do
       sign_in_as_user
-      assert_contain "Invalid email or password."
+      assert_contain "Invalid subdomain or password."
       assert_not warden.authenticated?(:user)
     end
   end