added tests for XmlMini#to_tag.

activesupport/test/test_xml_mini.rb

@@ -1,7 +1,9 @@
 require 'abstract_unit'
 require 'active_support/xml_mini'
+require 'active_support/builder'
 
-class XmlMiniTest < Test::Unit::TestCase
+module XmlMiniTest
+  class RenameKeyTest < Test::Unit::TestCase
     def test_rename_key_dasherizes_by_default
       assert_equal "my-key", ActiveSupport::XmlMini.rename_key("my_key")
     end
@@ -57,5 +59,42 @@ class XmlMiniTest < Test::Unit::TestCase
     def test_rename_key_does_not_dasherize_multiple_leading_underscores
       assert_equal "id__", ActiveSupport::XmlMini.rename_key("id__")
     end  
+  end
 
+  class ToTagTest < ActiveSupport::TestCase
+    def assert_xml(xml)
+      assert_equal xml, @options[:builder].target!
+    end
+    
+    setup do
+      @xml = ActiveSupport::XmlMini
+      @options = {:skip_instruct => true, :builder => Builder::XmlMarkup.new}
+    end
+    
+    test "#to_tag accepts a callable object and passes options with the builder" do
+      @xml.to_tag(:some_tag, lambda {|o| o[:builder].br }, @options)
+      assert_xml "<br/>"
+    end
+    
+    test "#to_tag accepts a callable object and passes options and tag name" do
+      @xml.to_tag(:tag, lambda {|o, t| o[:builder].b(t) }, @options)
+      assert_xml "<b>tag</b>"
+    end
+    
+    test "#to_tag accepts an object responding to #to_xml and passes the options, where :root is key" do
+      obj = Object.new
+      obj.instance_eval do
+        def to_xml(options) options[:builder].yo(options[:root].to_s) end
+      end
+      
+      @xml.to_tag(:tag, obj, @options)
+      assert_xml "<yo>tag</yo>"
+    end
+    
+    test "#to_tag accepts arbitrary objects responding to #to_str" do
+      @xml.to_tag(:b, "Howdy", @options)
+      assert_xml "<b>Howdy</b>"
+    end
+    # TODO: test the remaining functions hidden in #to_tag.
+  end
 end