Verbose be_valid RSpec matcher

gistfile1.rb

RSpec::Matchers.define :be_valid do
  match do |model|
    model.valid?
  end

  failure_message_for_should do |model|
    "expected valid? to return true, got false:\n #{model.errors.full_messages.join("\n ")}"
  end

  failure_message_for_should_not do |model|
    "expected valid? to return false, got true"
  end

  description do
    "be valid"
  end
end

gistfile2.txt

1) Video while creating should be valid
     Failure/Error: @video.should be_valid
       expected valid? to return true, got false due to the following errors:
        Youtube url is invalid
        Youtube url can't be blank
     # ./spec/models/video_spec.rb:29