Port test from cf1904f6 to avoid future regression

Related issue: #11939, #12084

activerecord/test/cases/inheritance_test.rb

@@ -313,8 +313,12 @@ def test_inheritance_without_mapping
     assert_kind_of SpecialSubscriber, SpecialSubscriber.find("webster132")
     assert_nothing_raised { s = SpecialSubscriber.new("name" => "And breaaaaathe!"); s.id = 'roger'; s.save }
   end
-end
 
+  def test_scope_inherited_properly
+    assert_nothing_raised { Company.of_first_firm }
+    assert_nothing_raised { Client.of_first_firm }
+  end
+end
 
 class InheritanceComputeTypeTest < ActiveRecord::TestCase
   fixtures :companies

activerecord/test/models/company.rb

@@ -11,6 +11,11 @@ class Company < AbstractCompany
   has_many :contracts
   has_many :developers, :through => :contracts
 
+  scope :of_first_firm, lambda {
+    joins(:account => :firm).
+    where('firms.id' => 1)
+  }
+
   def arbitrary_method
     "I am Jack's profound disappointment"
   end