Gotta love when you search the web and find nothing "how to test web components" is a wasteland.
It's no wonder - the designers of it did not seem to consider how one might test them in isolation. So far I have found two major problems I can't seem to work around:
• cannot access the object you are testing until element has been added to DOM and lifecycle methods called
• inability to mock/replace window or document, esp given the first problem