adds coverage for the issue addressed in fe43bbd8

[#4166 state:committed]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

activerecord/test/cases/associations_test.rb

@@ -180,6 +180,20 @@ def test_reload_returns_assocition
     end
   end
 
+  def test_splat_does_not_invoke_to_a_on_singular_targets
+    Kernel.module_eval do
+      alias original_to_a to_a
+      def to_a
+        [:_]
+      end
+    end
+    assert_not_equal [:_], [*posts(:welcome).author]
+  ensure
+    Kernel.module_eval do
+      alias to_a original_to_a
+    end
+  end
+
   def setup_dangling_association
     josh = Author.create(:name => "Josh")
     p = Post.create(:title => "New on Edge", :body => "More cool stuff!", :author => josh)