Show leaked instance variables in cucumber. A terrible hack but sometimes that is what ya need to do :)

cucumber_leaks.rb

$cucumber_instance_variables = []

Before do
  $cucumber_instance_variables = instance_variables
end

After do
  test_variables = instance_variables - $cucumber_instance_variables

  message = "[WARN] the following test variables could be leaking #{leaked_variables.join(', ')}"
  puts message if test_variables.any? and ENV['SHOW_TEST_VARS']

  test_variables.each {|v| instance_variable_set v, nil }
  $cucumber_instance_variables = []
end