if testem.js is imported multiple times within the same test page, it can cause the test run to half

[step2yeung]

I saw a situation where an additional <script> for testem.js was added to the index.html that is used to run the tests.

This was unnecessary because this is added during the build for an ember app. The problem it cause is calling init() more than once (https://github.com/testem/testem/blob/master/public/testem/testem_connection.js#L147), which will send additional browser-login events (https://github.com/testem/testem/blob/master/public/testem/testem_connection.js#L179) for the same browser instance.

The additional browser-login events causes the testem server to account for two browserTestRunner instance, when there really should only be one.
Testem will wait for the two browserTestRunner instance to complete, but in reality, there is only one executing browser. When the browser finishes running tests, one of the browserTestRunner instance completes, while testem waits for the second browserRunnerInstance.
Testem will timeout after it reached the timeout of 3600seconds set in testem.js.

I feel testem should either:

1. throw an error if init() is called more than once
   or
2. recognize that init() should only be ran once even if testem.js gets imported more than once

I personally would go with (1). I can put up a PR for this

[johanneswuerbach]

1. sounds good to me 👍