1) with class_name i've got ' undefined method `human' for "Post":String' in specs.

2) with form_buffers - because of form_buffers.pop (why?) it is not rendering elements inside block:
spec failed: Failure/Error: body.should have_tag("label", "Title 1")
because if we do not add anything to form buffer than the last element will be removed so that is why the label is not rendering during the test.