Add optional resource usage limitations to number of rendering calls, length of rendering output and/or number of variable/capture assignments

test/liquid/template_test.rb

@@ -71,4 +71,27 @@ class TemplateTest < Test::Unit::TestCase
     assert_equal '1', t.render(assigns)
     @global = nil
   end
+
+  def test_resource_limits
+    t = Template.parse("0123456789")
+    t.resource_limits = { :render_length_limit => 5 }
+    assert_raises(Liquid::MemoryError) { t.render() }
+    t.resource_limits = { :render_length_limit => 10 }
+    assert_equal "0123456789", t.render()
+    assert_not_nil t.resource_limits[:render_length_current]
+
+    t = Template.parse("{% for a in (1..100) %} foo {% endfor %}")
+    t.resource_limits = { :render_score_limit => 50 }
+    assert_raises(Liquid::MemoryError) { t.render() }
+    t.resource_limits = { :render_score_limit => 200 }
+    assert_equal (" foo " * 100), t.render()
+    assert_not_nil t.resource_limits[:render_score_current]
+
+    t = Template.parse("{% assign foo = 42 %}{% assign bar = 23 %}")
+    t.resource_limits = { :assign_score_limit => 1 }
+    assert_raises(Liquid::MemoryError) { t.render() }
+    t.resource_limits = { :assign_score_limit => 2 }
+    assert_equal "", t.render()
+    assert_not_nil t.resource_limits[:assign_score_current]
+  end
 end # TemplateTest