Add deprecation notices for <% %>.

  * The approach is to compile <% %> into a method call that checks whether
    the value returned from a block is a String. If it is, it concats to the buffer and
    prints a deprecation warning.
  * <%= %> uses exactly the same logic to compile the template, which first checks
    to see whether it's compiling a block.
  * This should have no impact on other uses of block in templates. For instance, in
    <% [1,2,3].each do |i| %><%= i %><% end %>, the call to each returns an Array,
    not a String, so the result is not concatenated
  * In two cases (#capture and #cache), a String can be returned that should *never*
    be concatenated. We have temporarily created a String subclass called NonConcattingString
    which behaves (and is serialized) identically to String, but is not concatenated
    by the code that handles deprecated <% %> block helpers. Once we remove support
    for <% %> block helpers, we can remove NonConcattingString.

7 files changed, 35 insertions, 23 deletions

diff --git a/actionpack/test/controller/caching_test.rb b/actionpack/test/controller/caching_test.rb
index a792752ef4..432433f976 100644
--- a/actionpack/test/controller/caching_test.rb
+++ b/actionpack/test/controller/caching_test.rb
@@ -617,7 +617,7 @@ class FragmentCachingTest < ActionController::TestCase
     fragment_computed = false
 
     buffer = 'generated till now -> '.html_safe
-    @controller.fragment_for(buffer, 'expensive') { fragment_computed = true }
+    buffer << @controller.fragment_for('expensive') { fragment_computed = true }
 
     assert fragment_computed
     assert_equal 'generated till now -> ', buffer
@@ -628,7 +628,7 @@ class FragmentCachingTest < ActionController::TestCase
     fragment_computed = false
 
     buffer = 'generated till now -> '.html_safe
-    @controller.fragment_for(buffer, 'expensive') { fragment_computed = true }
+    buffer << @controller.fragment_for('expensive') { fragment_computed = true }
 
     assert !fragment_computed
     assert_equal 'generated till now -> fragment content', buffer
@@ -742,15 +742,4 @@ CACHED
 
     assert_equal "  <p>Builder</p>\n", @store.read('views/test.host/functional_caching/formatted_fragment_cached')
   end
-
-  def test_js_formatted_fragment_caching
-    get :formatted_fragment_cached, :format => "js"
-    assert_response :success
-    expected_body = %(title = "Hey";\n$("element_1").visualEffect("highlight");\n) +
-      %($("element_2").visualEffect("highlight");\nfooter = "Bye";)
-    assert_equal expected_body, @response.body
-
-    assert_equal ['$("element_1").visualEffect("highlight");', '$("element_2").visualEffect("highlight");'],
-      @store.read('views/test.host/functional_caching/formatted_fragment_cached')
-  end
 end
diff --git a/actionpack/test/fixtures/layouts/block_with_layout.erb b/actionpack/test/fixtures/layouts/block_with_layout.erb
index f25b41271d..73ac833e52 100644
--- a/actionpack/test/fixtures/layouts/block_with_layout.erb
+++ b/actionpack/test/fixtures/layouts/block_with_layout.erb
@@ -1,3 +1,3 @@
-<% render(:layout => "layout_for_partial", :locals => { :name => "Anthony" }) do %>Inside from first block in layout<% "Return value should be discarded" %><% end %>
+<%= render(:layout => "layout_for_partial", :locals => { :name => "Anthony" }) do %>Inside from first block in layout<% "Return value should be discarded" %><% end %>
 <%= yield %>
-<% render(:layout => "layout_for_partial", :locals => { :name => "Ramm" }) do %>Inside from second block in layout<% end %>
+<%= render(:layout => "layout_for_partial", :locals => { :name => "Ramm" }) do %>Inside from second block in layout<% end %>
diff --git a/actionpack/test/fixtures/test/deprecated_nested_layout.erb b/actionpack/test/fixtures/test/deprecated_nested_layout.erb
new file mode 100644
index 0000000000..7b6dcbb6c7
--- /dev/null
+++ b/actionpack/test/fixtures/test/deprecated_nested_layout.erb
@@ -0,0 +1,3 @@
+<% content_for :title, "title" -%>
+<% content_for :column do -%>column<% end -%>
+<% render :layout => 'layouts/column' do -%>content<% end -%>
\ No newline at end of file
diff --git a/actionpack/test/fixtures/test/nested_layout.erb b/actionpack/test/fixtures/test/nested_layout.erb
index 7b6dcbb6c7..6078f74b4c 100644
--- a/actionpack/test/fixtures/test/nested_layout.erb
+++ b/actionpack/test/fixtures/test/nested_layout.erb
@@ -1,3 +1,3 @@
 <% content_for :title, "title" -%>
 <% content_for :column do -%>column<% end -%>
-<% render :layout => 'layouts/column' do -%>content<% end -%>
\ No newline at end of file
+<%= render :layout => 'layouts/column' do -%>content<% end -%>
\ No newline at end of file
diff --git a/actionpack/test/fixtures/test/using_layout_around_block.html.erb b/actionpack/test/fixtures/test/using_layout_around_block.html.erb
index a93fa02c9c..3d6661df9a 100644
--- a/actionpack/test/fixtures/test/using_layout_around_block.html.erb
+++ b/actionpack/test/fixtures/test/using_layout_around_block.html.erb
@@ -1 +1 @@
-<% render(:layout => "layout_for_partial", :locals => { :name => "David" }) do %>Inside from block<% end %>
\ No newline at end of file
+<%= render(:layout => "layout_for_partial", :locals => { :name => "David" }) do %>Inside from block<% end %>
\ No newline at end of file
diff --git a/actionpack/test/template/erb/tag_helper_test.rb b/actionpack/test/template/erb/tag_helper_test.rb
index cc96a43901..b5b7ae87de 100644
--- a/actionpack/test/template/erb/tag_helper_test.rb
+++ b/actionpack/test/template/erb/tag_helper_test.rb
@@ -20,7 +20,7 @@ module ERBTest
   end
 
   class DeprecatedViewContext < ViewContext
-    include ActionView::Helpers::DeprecatedBlockHelpers
+    # include ActionView::Helpers::DeprecatedBlockHelpers
   end
 
   module SharedTagHelpers
@@ -31,28 +31,36 @@ module ERBTest
       ActionView::Template::Handlers::Erubis.new(template).evaluate(context.new)
     end
 
+    def maybe_deprecated
+      if @deprecated
+        assert_deprecated { yield }
+      else
+        yield
+      end
+    end
+
     test "percent equals works for content_tag and does not require parenthesis on method call" do
-      assert_equal "<div>Hello world</div>", render_content("content_tag :div", "Hello world")
+      maybe_deprecated { assert_equal "<div>Hello world</div>", render_content("content_tag :div", "Hello world") }
     end
 
     test "percent equals works for javascript_tag" do
       expected_output = "<script type=\"text/javascript\">\n//<![CDATA[\nalert('Hello')\n//]]>\n</script>"
-      assert_equal expected_output, render_content("javascript_tag", "alert('Hello')")
+      maybe_deprecated { assert_equal expected_output, render_content("javascript_tag", "alert('Hello')") }
     end
 
     test "percent equals works for javascript_tag with options" do
       expected_output = "<script id=\"the_js_tag\" type=\"text/javascript\">\n//<![CDATA[\nalert('Hello')\n//]]>\n</script>"
-      assert_equal expected_output, render_content("javascript_tag(:id => 'the_js_tag')", "alert('Hello')")
+      maybe_deprecated { assert_equal expected_output, render_content("javascript_tag(:id => 'the_js_tag')", "alert('Hello')") }
     end
 
     test "percent equals works with form tags" do
       expected_output = "<form action=\"foo\" method=\"post\">hello</form>"
-      assert_equal expected_output, render_content("form_tag('foo')", "<%= 'hello' %>")
+      maybe_deprecated { assert_equal expected_output, render_content("form_tag('foo')", "<%= 'hello' %>") }
     end
 
     test "percent equals works with fieldset tags" do
       expected_output = "<fieldset><legend>foo</legend>hello</fieldset>"
-      assert_equal expected_output, render_content("field_set_tag('foo')", "<%= 'hello' %>")
+      maybe_deprecated { assert_equal expected_output, render_content("field_set_tag('foo')", "<%= 'hello' %>") }
     end
   end
 
@@ -77,6 +85,10 @@ module ERBTest
       "<% __in_erb_template=true %><% #{str} do %>#{rest}<% end %>"
     end
 
+    def setup
+      @deprecated = true
+    end
+
     include SharedTagHelpers
   end
 end
\ No newline at end of file
diff --git a/actionpack/test/template/render_test.rb b/actionpack/test/template/render_test.rb
index cea8ab1bce..e66202e8fe 100644
--- a/actionpack/test/template/render_test.rb
+++ b/actionpack/test/template/render_test.rb
@@ -228,6 +228,14 @@ module RenderTestCases
       @view.render(:file => "test/hello_world.erb", :layout => "layouts/yield")
   end
 
+  # TODO: Move to deprecated_tests.rb
+  def test_render_with_nested_layout_deprecated
+    assert_deprecated do
+      assert_equal %(<title>title</title>\n\n\n<div id="column">column</div>\n<div id="content">content</div>\n),
+        @view.render(:file => "test/deprecated_nested_layout.erb", :layout => "layouts/yield")
+    end
+  end
+
   def test_render_with_nested_layout
     assert_equal %(<title>title</title>\n\n\n<div id="column">column</div>\n<div id="content">content</div>\n),
       @view.render(:file => "test/nested_layout.erb", :layout => "layouts/yield")