Test Mode appears to not be working

[Cloud Login]

v 0.11
Converting to test mode for my test suite. This code sends a message not in test mode

@mailgun = Mailgun(api_key: ENV['MAILGUN_API_KEY'], domain: ENV['MAILGUN_DOMAIN'], test_mode: true )
message_params = {
      from: ENV['MAILGUN_USER_NAME'],
      to: "[e-mail]",
      subject: "You've been invited to join the BlueStreak Platform!",
      html: html_output.to_str
    }.merge(opts)
   @mailgun.messages.send_email(message_params)

And (part of) the mailgun logs for my request:

...
flags": {
        "is-routed": false,
        "is-authenticated": true,
        "is-system-test": false,
        "is-test-mode": false
    },
...

Note the "is-test-mode": false