Raises ArgumentError when try to define a scope without a callable

This changes the actual exception `NoMethodError: undefined method `call'
for #<ActiveRecord::Relation []>` to a `ArgumentError` when try to define
a scope without a callable.

1 files changed, 3 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/scoping/named.rb b/activerecord/lib/active_record/scoping/named.rb
index 49cadb66d0..04aeeeb4fa 100644
--- a/activerecord/lib/active_record/scoping/named.rb
+++ b/activerecord/lib/active_record/scoping/named.rb
@@ -139,6 +139,9 @@ module ActiveRecord
         #   Article.published.featured.latest_article
         #   Article.featured.titles
         def scope(name, body, &block)
+          raise ArgumentError, 'You need to suply a callable as scope body' unless
+            body.respond_to?(:call)
+
           if dangerous_class_method?(name)
             raise ArgumentError, "You tried to define a scope named \"#{name}\" " \
               "on the model \"#{self.name}\", but Active Record already defined " \