adds test coverage for with_output_buffer

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

actionpack/test/template/capture_helper_test.rb

@@ -3,6 +3,7 @@ require 'abstract_unit'
 class CaptureHelperTest < ActionView::TestCase
   def setup
     super
+    @av = ActionView::Base.new
     @_content_for = Hash.new {|h,k| h[k] = "" }
   end
 
@@ -13,9 +14,50 @@ class CaptureHelperTest < ActionView::TestCase
     assert ! content_for?(:something_else)
   end
 
+  def test_with_output_buffer_swaps_the_output_buffer_given_no_argument
+    assert_nil @av.output_buffer
+    buffer = @av.with_output_buffer do
+      @av.output_buffer << '.'
+    end
+    assert_equal '.', buffer
+    assert_nil @av.output_buffer
+  end
+
+  def test_with_output_buffer_swaps_the_output_buffer_with_an_argument
+    assert_nil @av.output_buffer
+    buffer = ActionView::OutputBuffer.new('.')
+    @av.with_output_buffer(buffer) do
+      @av.output_buffer << '.'
+    end
+    assert_equal '..', buffer
+    assert_nil @av.output_buffer
+  end
+
+  def test_with_output_buffer_restores_the_output_buffer
+    buffer = ActionView::OutputBuffer.new
+    @av.output_buffer = buffer
+    @av.with_output_buffer do
+      @av.output_buffer << '.'
+    end
+    assert buffer.equal?(@av.output_buffer)
+  end
+
+  unless RUBY_VERSION < '1.9'
+    def test_with_output_buffer_sets_proper_encoding
+      @av.output_buffer = ActionView::OutputBuffer.new
+
+      # Ensure we set the output buffer to an encoding different than the default one.
+      alt_encoding = @av.output_buffer.encoding == Encoding::US_ASCII ? Encoding::UTF_8 : Encoding::US_ASCII
+      @av.output_buffer.force_encoding(alt_encoding)
+
+      @av.with_output_buffer do
+        assert alt_encoding, @av.output_buffer.encoding
+      end
+    end
+  end
+
   def test_with_output_buffer_does_not_assume_there_is_an_output_buffer
-    av = ActionView::Base.new
-    assert_nil av.output_buffer
-    assert_equal "", av.with_output_buffer {}
+    assert_nil @av.output_buffer
+    assert_equal "", @av.with_output_buffer {}
   end
 end