I just released a new gem on GitHub that provides some common validation expectations to rspec. Instead of writing specs to verify that your models are handling validation correctly, these expectations simply check that the validation is getting declared correctly in your model. For example:

describe User do
  it_should_validate_presence_of :first_name, :last_name, :email
  it_should_validate_numericality_of :zip
  it_should_validate_uniqueness_of :email
end

Since the expectations never hit the database, they are also faster than testing the traditional way. It’s dead simple to install on Rails 2.1 or later:

script/plugin install git://github.com/pelargir/rspec_validation_expectations.git

The expectations become available to your specs immediately.