concat should ignore nil

2 files changed, 9 insertions, 1 deletions

diff --git a/actionpack/lib/action_view/helpers/text_helper.rb b/actionpack/lib/action_view/helpers/text_helper.rb
index 3be4843386..f81f7eded6 100644
--- a/actionpack/lib/action_view/helpers/text_helper.rb
+++ b/actionpack/lib/action_view/helpers/text_helper.rb
@@ -26,7 +26,7 @@ module ActionView
       #       # will either display "Logged in!" or a login link
       #   %>
       def concat(string)
-        if @output_buffer
+        if @output_buffer && string
           @output_buffer << string
         else
           string
diff --git a/actionpack/test/template/text_helper_test.rb b/actionpack/test/template/text_helper_test.rb
index 62cdca03d1..0f5c62acad 100644
--- a/actionpack/test/template/text_helper_test.rb
+++ b/actionpack/test/template/text_helper_test.rb
@@ -11,6 +11,14 @@ class TextHelperTest < ActionView::TestCase
     @_cycles = nil if (defined? @_cycles)
   end
 
+  def test_concat
+    @output_buffer = 'foo'
+    concat 'bar'
+    assert_equal 'foobar', @output_buffer
+    assert_nothing_raised { concat nil }
+    assert_equal 'foobar', @output_buffer
+  end
+
   def test_simple_format
     assert_equal "<p></p>", simple_format(nil)