Split resource build for sign up into method to allow override

Author: mcelicalderon

app/graphql/graphql_devise/mutations/sign_up.rb

@@ -7,7 +7,7 @@ class SignUp < Base
       argument :confirm_success_url,   String, required: false
 
       def resolve(confirm_success_url: nil, **attrs)
-        resource = resource_class.new(provider: provider, **attrs)
+        resource = build_resource(attrs)
         raise_user_error(I18n.t('graphql_devise.resource_build_failed')) if resource.blank?
 
         redirect_url = confirm_success_url || DeviseTokenAuth.default_confirm_success_url
@@ -45,6 +45,10 @@ def resolve(confirm_success_url: nil, **attrs)
 
       private
 
+      def build_resource(attrs)
+        resource_class.new(attrs.merge(provider: provider))
+      end
+
       def provider
         :email
       end