[dm-validations] Validate presence only when Property#allow_blank? is…

… true

[#935]

dm-validations/lib/dm-validations/auto_validate.rb

@@ -111,8 +111,8 @@ def auto_generate_validations(property)
       def disabled_auto_validations?
         @disable_auto_validations || false
       end
-      alias auto_validations_disabled? disabled_auto_validations?
 
+      alias auto_validations_disabled? disabled_auto_validations?
 
       # Checks whether or not property should be auto validated.
       # It is the case for properties with :auto_validation option
@@ -125,7 +125,7 @@ def skip_auto_validation_for?(property)
       end
 
       def infer_presence_validation_for(property, options)
-        return if allow_nil?(property)
+        return if skip_presence_validation?(property)
 
         validates_present property.name, options_with_message(options, property, :presence)
       end
@@ -193,8 +193,8 @@ def infer_type_validation_for(property, options)
 
       private
 
-      def allow_nil?(property)
-        property.allow_nil? || property.serial?
+      def skip_presence_validation?(property)
+        property.allow_blank? || property.serial?
       end
     end # module AutoValidate
   end # module Validate