module Shoulda::Macros

def should_not_change(description, &block)

end
should_not_change("the number of posts") { Post.count }
setup { @post.update_attributes(:title => "new") }
context "Updating a post" do

Example:

The passed description will be used when generating the test name and failure message.

is run. This is the logical opposite of should_change.
of a block that is run before and after the current setup block
Macro that creates a test asserting no change between the return value 
def should_not_change(description, &block)
  if block_given?
    code = block
  else
    warn "[DEPRECATION] should_not_change(expression) is deprecated. " <<
         "Use should_not_change(description) { code } instead."
    code = lambda { eval(description) }
  end
  before = lambda { @_before_should_not_change = code.bind(self).call }
  should "not change #{description}", :before => before do
    new_value = code.bind(self).call
    assert_equal @_before_should_not_change, new_value, "#{description} changed"
  end
end