Revert "Raise UnknownAttributeError when unknown attributes are supplied via mass assignment"

This reverts commit 108db00a.

activerecord/lib/active_record/base.rb

@@ -122,10 +122,6 @@ class DangerousAttributeError < ActiveRecordError
   class MissingAttributeError < NoMethodError
   end
 
-  # Raised when unknown attributes are supplied via mass assignment.
-  class UnknownAttributeError < NoMethodError
-  end
-
   # Raised when an error occurred while doing a mass assignment to an attribute through the
   # <tt>attributes=</tt> method. The exception has an +attribute+ property that is the name of the
   # offending attribute.
@@ -2441,11 +2437,7 @@ def attributes=(new_attributes, guard_protected_attributes = true)
         attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes
 
         attributes.each do |k, v|
-          if k.include?("(")
-            multi_parameter_attributes << [ k, v ]
-          else
-            respond_to?(:"#{k}=") ? send(:"#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}")
-          end
+          k.include?("(") ? multi_parameter_attributes << [ k, v ] : send(k + "=", v)
         end
 
         assign_multiparameter_attributes(multi_parameter_attributes)

activerecord/test/cases/base_test.rb

@@ -904,14 +904,6 @@ def test_customized_primary_key_remains_protected_when_referred_to_as_id
     assert_nil keyboard.id
   end
 
-  def test_mass_assigning_invalid_attribute
-    firm = Firm.new
-
-    assert_raises(ActiveRecord::UnknownAttributeError) do
-      firm.attributes = { "id" => 5, "type" => "Client", "i_dont_even_exist" => 20 }
-    end
-  end
-
   def test_mass_assignment_protection_on_defaults
     firm = Firm.new
     firm.attributes = { "id" => 5, "type" => "Client" }