Using stderr instead of stdout

test/helper.rb

@@ -70,4 +70,14 @@ class Test::Unit::TestCase
   ensure
     $stdout = $old_stdout
   end
+
+  def capture_stderr
+    $old_stderr = $stderr
+    $stderr = StringIO.new
+    yield
+    $stderr.rewind
+    return $stderr.string
+  ensure
+    $stderr = $old_stderr
+  end
 end

test/test_convertible.rb

@@ -21,7 +21,7 @@ class TestConvertible < Test::Unit::TestCase
 
     should "not parse if there is syntax error in front-matter" do
       name = 'broken_front_matter2.erb'
-      out = capture_stdout do
+      out = capture_stderr do
         ret = @convertible.read_yaml(@base, name)
         assert_equal({}, ret)
       end
@@ -30,7 +30,7 @@ class TestConvertible < Test::Unit::TestCase
     end
 
     should "not allow ruby objects in yaml" do
-      out = capture_stdout do
+      out = capture_stderr do
         @convertible.read_yaml(@base, 'exploit_front_matter.erb')
       end
       assert_no_match /undefined class\/module DoesNotExist/, out
@@ -38,7 +38,7 @@ class TestConvertible < Test::Unit::TestCase
 
     should "not parse if there is encoding error in file" do
       name = 'broken_front_matter3.erb'
-      out = capture_stdout do
+      out = capture_stderr do
         ret = @convertible.read_yaml(@base, name, :encoding => 'utf-8')
         assert_equal({}, ret)
       end