Add emitter unit tests

[yiliansource]

Is your feature request related to a problem? Please describe.
Its hard to be sure if the emitter functions precisely as intended currently. The effects caused by it have to be eyeballed.

Describe the solution you'd like
Proper coverage of the emitter class using unit tests. Since it's functionality is time (tick) based, some tolerance can be applied.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.