Fix weirdness with partials in ERB [sinatra#158]

CHANGES

@@ -18,6 +18,8 @@
  * Fix :provides causing crash on any request when request has no
    Accept header [#139]
  * Fix that ERB templates were evaluated twice per "erb" call.
+ * The ERB output buffer is now available to helpers via the @_out_buf
+   instance variable.
 
 = 0.9.0.4 / 2009-01-25
 

lib/sinatra/base.rb

@@ -281,12 +281,17 @@ def template_path(engine, template, options={})
     end
 
     def render_erb(template, data, options, &block)
+      original_out_buf = @_out_buf
       data = data.call if data.kind_of? Proc
+
       instance = ::ERB.new(data, nil, nil, '@_out_buf')
       locals = options[:locals] || {}
       locals_assigns = locals.to_a.collect { |k,v| "#{k} = locals[:#{k}]" }
+
       src = "#{locals_assigns.join("\n")}\n#{instance.src}"
       eval src, binding, '(__ERB__)', locals_assigns.length + 1
+      @_out_buf, result = original_out_buf, @_out_buf
+      result
     end
 
     def render_haml(template, data, options, &block)

test/erb_test.rb

@@ -64,4 +64,18 @@ def is; "IS." end
     assert ok?
     assert_equal 'THIS. IS. SPARTA!', body
   end
+
+  it "can be used in a nested fashion for partials and whatnot" do
+    mock_app {
+      template(:inner) { "<inner><%= 'hi' %></inner>" }
+      template(:outer) { "<outer><%= erb :inner %></outer>" }
+      get '/' do
+        erb :outer
+      end
+    }
+
+    get '/'
+    assert ok?
+    assert_equal '<outer><inner>hi</inner></outer>', body
+  end
 end