Raise NameError instead of ArgumentError in ActiveSupport::Dependencies

ActiveSupport::Dependencies now raises NameError if it finds an existing
constant in load_missing_constant. This better reflects the nature of
the error which is usually caused by calling constantize on a nested constant.

Closes #1423

2 files changed, 7 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index f74810720d..08cc282d09 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1308,7 +1308,6 @@ MSG
               rescue NameError => e
                 # We don't want to swallow NoMethodError < NameError errors
                 raise e unless e.instance_of?(NameError)
-              rescue ArgumentError
               end
             end
 
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 39043447fc..2224097f04 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1766,6 +1766,13 @@ class BasicsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_compute_type_argument_error
+    ActiveSupport::Dependencies.stubs(:constantize).raises(ArgumentError)
+    assert_raises ArgumentError do
+      ActiveRecord::Base.send :compute_type, 'InvalidModel'
+    end
+  end
+
   def test_clear_cache!
     # preheat cache
     c1 = Post.columns