```ruby
Autotest.add_discovery do
  "cucumber" if ENV['AUTOFEATURE'] == 'true' && File.directory?('features')
end
```

Add warning when AUTOFEATURE is disabled.
user
```ruby
Autotest.add_discovery do
  if File.directory?('features')
    if ENV['AUTOFEATURE'] == 'true'
      "cucumber"
    else
      puts "(Not running features.  To run features in autotest, set AUTOFEATURE=true.)"
    end
  end
end
```
assistant