Merge pull request #519 from Shopify/remove-filter-method-blacklist

Allow filters to redefine Object methods to make them invokable.

test/integration/filter_test.rb

@@ -25,6 +25,12 @@ end
 class FiltersTest < Minitest::Test
   include Liquid
 
+  module OverrideObjectMethodFilter
+    def tap(input)
+      "tap overridden"
+    end
+  end
+
   def setup
     @context = Context.new
   end
@@ -105,6 +111,13 @@ class FiltersTest < Minitest::Test
     output = Variable.new(%! 'hello %{first_name}, %{last_name}' | substitute: first_name: surname, last_name: 'doe' !).render(@context)
     assert_equal 'hello john, doe', output
   end
+
+  def test_override_object_method_in_filter
+    assert_equal "tap overridden", Template.parse("{{var | tap}}").render!({ 'var' => 1000 }, :filters => [OverrideObjectMethodFilter])
+
+    # tap still treated as a non-existent filter
+    assert_equal "1000", Template.parse("{{var | tap}}").render!({ 'var' => 1000 })
+  end
 end
 
 class FiltersInTemplate < Minitest::Test

test/test_helper.rb

@@ -48,13 +48,19 @@ module Minitest
     end
 
     def with_global_filter(*globals)
-      original_filters = Array.new(Liquid::Strainer.class_variable_get(:@@filters))
+      original_global_strainer = Liquid::Strainer.class_variable_get(:@@global_strainer)
+      Liquid::Strainer.class_variable_set(:@@global_strainer, Class.new(Liquid::Strainer) do
+        @filter_methods = Set.new
+      end)
+      Liquid::Strainer.class_variable_get(:@@strainer_class_cache).clear
+
       globals.each do |global|
         Liquid::Template.register_filter(global)
       end
       yield
     ensure
-      Liquid::Strainer.class_variable_set(:@@filters, original_filters)
+      Liquid::Strainer.class_variable_get(:@@strainer_class_cache).clear
+      Liquid::Strainer.class_variable_set(:@@global_strainer, original_global_strainer)
     end
 
     def with_taint_mode(mode)

test/unit/strainer_unit_test.rb

@@ -31,11 +31,11 @@ class StrainerUnitTest < Minitest::Test
 
   def test_strainer_only_invokes_public_filter_methods
     strainer = Strainer.create(nil)
-    assert_equal false, strainer.invokable?('__test__')
-    assert_equal false, strainer.invokable?('test')
-    assert_equal false, strainer.invokable?('instance_eval')
-    assert_equal false, strainer.invokable?('__send__')
-    assert_equal true, strainer.invokable?('size') # from the standard lib
+    assert_equal false, strainer.class.invokable?('__test__')
+    assert_equal false, strainer.class.invokable?('test')
+    assert_equal false, strainer.class.invokable?('instance_eval')
+    assert_equal false, strainer.class.invokable?('__send__')
+    assert_equal true, strainer.class.invokable?('size') # from the standard lib
   end
 
   def test_strainer_returns_nil_if_no_filter_method_found
@@ -63,9 +63,7 @@ class StrainerUnitTest < Minitest::Test
     assert_kind_of Strainer, strainer
     assert_kind_of a, strainer
     assert_kind_of b, strainer
-    Strainer.class_variable_get(:@@filters).each do |m|
-      assert_kind_of m, strainer
-    end
+    assert_kind_of Liquid::StandardFilters, strainer
   end
 
 end # StrainerTest