Fix commit 7bbb4ff84f192a6a2292 so it's backwards-compatible

lib/liquid/file_system.rb

@@ -14,7 +14,7 @@ module Liquid
   # This will parse the template with a LocalFileSystem implementation rooted at 'template_path'.
   class BlankFileSystem
     # Called by Liquid to retrieve a template file
-    def read_template_file(context, template_name)
+    def read_template_file(template_path, context)
       raise FileSystemError, "This liquid context does not allow includes."
     end
   end
@@ -38,8 +38,7 @@ module Liquid
       @root = root
     end
     
-    def read_template_file(context, template_name)
-      template_path = context[template_name]
+    def read_template_file(template_path, context)
       full_path = full_path(template_path)
       raise FileSystemError, "No such template '#{template_path}'" unless File.exists?(full_path)
       

lib/liquid/tags/include.rb

@@ -22,12 +22,10 @@ module Liquid
   
     def parse(tokens)      
     end
-  
+    
     def render(context)      
-      file_system = context.registers[:file_system] || Liquid::Template.file_system
-      source  = file_system.read_template_file(context, @template_name)
+      source = _read_template_from_file_system(context)
       partial = Liquid::Template.parse(source)      
-      
       variable = context[@variable_name || @template_name[1..-2]]
       
       context.stack do
@@ -50,6 +48,21 @@ module Liquid
         end
       end
     end
+   
+    private
+      def _read_template_from_file_system(context)
+        file_system = context.registers[:file_system] || Liquid::Template.file_system
+      
+        # make read_template_file call backwards-compatible.
+        case file_system.method(:read_template_file).arity
+        when 1
+          file_system.read_template_file(context[@template_name])
+        when 2
+          file_system.read_template_file(context[@template_name], context)
+        else
+          raise ArgumentError, "file_system.read_template_file expects two parameters: (template_name, context)"
+        end
+      end
   end
 
   Template.register_tag('include', Include)  

test/lib/liquid/file_system_test.rb

@@ -5,7 +5,7 @@ class FileSystemTest < Test::Unit::TestCase
 
   def test_default
     assert_raise(FileSystemError) do
-      BlankFileSystem.new.read_template_file({'dummy'=>'smarty'}, "dummy")
+      BlankFileSystem.new.read_template_file("dummy", {'dummy'=>'smarty'})
     end
   end
 

test/lib/liquid/include_tag_test.rb

@@ -1,8 +1,7 @@
 require 'test_helper'
 
 class TestFileSystem
-  def read_template_file(context, template_name)
-    template_path = context[template_name]
+  def read_template_file(template_path, context)
     case template_path
     when "product"
       "Product: {{ product.title }} "
@@ -35,8 +34,7 @@ class TestFileSystem
 end
 
 class OtherFileSystem
-  def read_template_file(context, template_name)
-    template_path = context[template_name]
+  def read_template_file(template_path, context)
     'from OtherFileSystem'
   end
 end
@@ -106,7 +104,7 @@ class IncludeTagTest < Test::Unit::TestCase
   def test_recursively_included_template_does_not_produce_endless_loop
 
     infinite_file_system = Class.new do
-      def read_template_file(context, template_name)
+      def read_template_file(template_path, context)
         "-{% include 'loop' %}"
       end
     end
@@ -119,6 +117,18 @@ class IncludeTagTest < Test::Unit::TestCase
 
   end
 
+  def test_backwards_compatability_support_for_overridden_read_template_file
+    infinite_file_system = Class.new do
+      def read_template_file(template_path) # testing only one argument here.
+        "- hi mom"
+      end
+    end
+
+    Liquid::Template.file_system = infinite_file_system.new
+
+    Template.parse("{% include 'hi_mom' %}").render!
+  end
+
   def test_dynamically_choosen_template
 
     assert_equal "Test123", Template.parse("{% include template %}").render("template" => 'Test123')