Merge pull request #210 from saghaulor/attr_was_fix

Fix attr_was method.

lib/attr_encrypted/adapters/active_record.rb

@@ -59,8 +59,10 @@ def attr_encrypted(*attrs)
             end
 
             define_method("#{attr}_was") do
-              iv_and_salt = { iv: send("#{options[:attribute]}_iv_was"), salt: send("#{options[:attribute]}_salt_was"), operation: :decrypting }
-              encrypted_attributes[attr].merge!(iv_and_salt)
+              attr_was_options = { operation: :decrypting }
+              attr_was_options[:iv]= send("#{options[:attribute]}_iv_was") if respond_to?("#{options[:attribute]}_iv_was")
+              attr_was_options[:salt]= send("#{options[:attribute]}_salt_was") if respond_to?("#{options[:attribute]}_salt_was")
+              encrypted_attributes[attr].merge!(attr_was_options)
               evaluated_options = evaluated_attr_encrypted_options_for(attr)
               [:iv, :salt, :operation].each { |key| encrypted_attributes[attr].delete(key) }
               self.class.decrypt(attr, send("#{options[:attribute]}_was"), evaluated_options)

test/active_record_test.rb

@@ -192,6 +192,12 @@ def test_should_create_was_predicate
     assert_equal original_email, person.email_was
     person.email = 'test2@example.com'
     assert_equal original_email, person.email_was
+    old_pm_name = "Winston Churchill"
+    pm = PrimeMinister.create!(name: old_pm_name)
+    assert_equal old_pm_name, pm.name_was
+    old_zipcode = "90210"
+    address = Address.create!(zipcode: old_zipcode, mode: "single_iv_and_salt")
+    assert_equal old_zipcode, address.zipcode_was
   end
 
   if ::ActiveRecord::VERSION::STRING > "4.0"