gcloud CLI integration & Firebase test lab about sylph

[mmcc007]

Recently looked into this. Firebase Test Lab is designed differently from AWS Device Farm. Whereas Device Farm has a VM with a device attached that is called via aws cli, Test Lab has no VM and is 'no-host/self-test' that is called via gcloud cli.

This means that Flutter team may have to go with a different approach to testing in order to run on Test Lab. There are 2 projects that are addressing this approach:
https://pub.dev/packages/espresso
https://pub.dev/packages/e2e
Both appear to involve knowledge of running tests natively (using Java/Swift, etc...). Though I think the e2e package is the main path forward and just uses boilerplate for native part, so test remains in dart.

It is not clear if this will be the only path going forward, or if there will still be support for FlutterDriver. There is some discussion of writing a tool to migrate to new approach. May have to wait for dust to settle before integrating with sylph.

You can track progress on development of e2e package (otherwise known as changes to WidgetTester) on:
flutter/flutter#30214

If you get something working on Test Lab, let me know.