Use Async WebDiver in Tests #591

Current Situation

Currently, we run tests which rely on the browser using a synchronously executing web driver from Selenium. As a result, server implementations have been required to provide a run_in_thread method such that they can be run in the background while the blocking test code is allowed to proceed.

Unfortunately, some async servers don't play well with threads. This is primarily due to the fact that cleanly stopping a thread can be somewhat challenging. For example, IDOM is currently locked into version sanic<19.12 because later releases have been developed without consideration for threading.

Proposed Actions

As a result, we should switch to an async web driver like arsenic or pyppeteer and add a ServerType.run_async method to the various server implementations. Once this is done we can deprecate the ServerType.run_in_thread method.

Then lastly, we can upgrade Sanic to the latest version.

Work Items

• Implement ServerType.run_async and switch to async web driver
• Mark ServerType.run_in_thread as deprecated
• Update downstream libraries (e.g. custom component template and anything made from it).
• Upgrade sanic and raise when run_in_thread is called for sanic>=19.12
• Remove ServerType.run_in_thread