Fix regression in range lookup

lib/liquid/range_lookup.rb

@@ -16,9 +16,22 @@ module Liquid
     end
 
     def evaluate(context)
-      start_int = Utils.to_integer(context.evaluate(@start_obj), true)
-      end_int = Utils.to_integer(context.evaluate(@end_obj), true)
+      start_int = to_integer(context.evaluate(@start_obj))
+      end_int = to_integer(context.evaluate(@end_obj))
       start_int..end_int
     end
+
+    private
+
+    def to_integer(input)
+      case input
+      when Integer
+        input
+      when NilClass, String
+        input.to_i
+      else
+        Utils.to_integer(input)
+      end
+    end
   end
 end

lib/liquid/utils.rb

@@ -33,14 +33,13 @@ module Liquid
       segments
     end
 
-    def self.to_integer(num, accept_invalid = false)
+    def self.to_integer(num)
       return num if num.is_a?(Integer)
       num = num.to_s
       begin
         Integer(num)
       rescue ::ArgumentError
-        raise Liquid::ArgumentError, "invalid integer" unless accept_invalid
-        0
+        raise Liquid::ArgumentError, "invalid integer"
       end
     end
 

test/integration/tags/for_tag_test.rb

@@ -42,6 +42,8 @@ HERE
     assert_raises(Liquid::ArgumentError) do
       Template.parse('{% for i in (a..2) %}{% endfor %}').render!("a" => [1, 2])
     end
+
+    assert_template_result(' 0  1  2  3 ', '{% for item in (a..3) %} {{item}} {% endfor %}', "a" => "invalid integer")
   end
 
   def test_for_with_variable_range