Fix sanitize_for_mass_assigment when role is nil

There is an example in Rails documentation that suggests implementing
assign_attributes method for ActiveModel interface, that by default
sends option role with nil. Since mass_assignment_authorizer never
is called without args, we can move the default value internally.

1 files changed, 3 insertions, 3 deletions

diff --git a/activemodel/lib/active_model/mass_assignment_security.rb b/activemodel/lib/active_model/mass_assignment_security.rb
index 13495d6786..95de039676 100644
--- a/activemodel/lib/active_model/mass_assignment_security.rb
+++ b/activemodel/lib/active_model/mass_assignment_security.rb
@@ -226,12 +226,12 @@ module ActiveModel
 
   protected
 
-    def sanitize_for_mass_assignment(attributes, role = :default)
+    def sanitize_for_mass_assignment(attributes, role = nil)
       _mass_assignment_sanitizer.sanitize(attributes, mass_assignment_authorizer(role))
     end
 
-    def mass_assignment_authorizer(role = :default)
-      self.class.active_authorizer[role]
+    def mass_assignment_authorizer(role)
+      self.class.active_authorizer[role || :default]
     end
   end
 end