Problem

You would like to upgrade your rails project from using rspec-rails 2.x to the latest rspec-rails 3.x version. According to the rspec-rails documentation the new 3.x includes many breaking changes.

Solution

The full instructions for upgrading from rspec-rails 2.x to rspec-rails 3.x are here, but you may not need to complete all the steps described in there.
So you could try with the following shorter steps:

• Run your rspec tests and make sure that they all pass
• Upgrade your rspec-rails to the version 2.99 provided by the rspec-rails team
• Run your rspec tests again, and you should have deprecation warnings. Usually that would consist of:

  spec-rails 3 will no longer automatically infer an 
  example group's spec type from the file location. 
  You can explicitly opt-in to this feature using 
  this snippet:
  
  RSpec.configure do |config|
    config.infer_spec_type_from_file_location!
  end

  which you could add to your spec/spec_helper.rb file

• Run your rspec tests again and this time they should have no deprecation warnings
• If they all pass then upgrade to the latest rspec-rails (ie 3.0.1).
• Run your rspec tests again, and this time you should normally have one deprecation warning:

  Requiring `rspec/autorun` when running RSpec via the `rspec` 
  command is deprecated. 
  Called from /xxx/xx/lib/active_support/dependencies.rb:247:
  in `require'.

• Delete the line require ‘rspec/autorun’ from your spec/spec_helper.rb file
• Rerun your tests and they should all be passing in rspec-rails 3.x now