Not as easy as you'd think. <a href='http://rspec.lighthouseapp.com/projects/5645/tickets/376-eval_erb-not-recognizing-instance-variables-in-before'>This bug</a> is relevant. It seems that not only can you not create your instance variables outside the ERB and pass them in, you can't even reliably create them inside the ERB. I ended up doing this: [ruby] def eval_erb(text) ERB.new(text).result(binding) end describe SomeHelper do it "should work" do @result = eval_erb <<-ERB <% my_helper_name(MyThing.new(:body=>"foo") do %> this stuff is passed as the block text <% end %> ERB @result.should == "exactly what I want" end end [/ruby] 1 2008-10-13T08:24:02-04:00 157 2008-10-13T08:24:26-04:00