class RSpec::Core::Metadata

def ensure_valid_keys(user_metadata)
  RESERVED_KEYS.each do |key|
    if user_metadata.keys.include?(key)
      raise <<-EOM
50}
} is not allowed
reserves some hash keys for its own internal use,
ing :#{key}, which is used on:
ller(0)[4]}.
re all of RSpec's reserved hash keys:
SERVED_KEYS.join("\n  ")}
50}
      raise ":#{key} is not allowed"
    end
  end
end