text: Title: Add basic testcases for the audioservice interface
  Body: Add tests for the [audioservice](https://github.com/MycroftAI/mycroft-core/blob/dev/mycroft/skills/audioservice.py) interface for skills.
  
  Basically the tests need to create a mock bus and create the audioservice with
  
  ```python
  bus_mock = Mock()`
  as = AudioService(bus_mock)
  ```
  
  Then do calls against the objects methods and ensure that the expected messages are sent on the mock_bus.
  
  If there are questions just comment here or join [our chat](https://chat.mycroft.ai)! 