add test case

activerecord/test/cases/validations/presence_validation_test.rb

@@ -3,6 +3,8 @@
 require 'models/man'
 require 'models/face'
 require 'models/interest'
+require 'models/speedometer'
+require 'models/dashboard'
 
 class PresenceValidationTest < ActiveRecord::TestCase
   class Boy < Man; end
@@ -48,4 +50,19 @@ def test_validates_presence_of_has_many_marked_for_destruction
     i2.mark_for_destruction
     assert b.invalid?
   end
+
+
+  def test_validates_presence_doesnt_convert_to_array
+    Speedometer.validates_presence_of :dashboard
+
+    dash = Dashboard.new
+
+    # dashboard has to_a method
+    def dash.to_a; ['(/)', '(\)']; end
+
+    s = Speedometer.new
+    s.dashboard = dash
+
+    assert_nothing_raised { s.valid? }
+  end
 end