We should have basic screenshot tests running on real devices to catch rendering regressions in the engine and framework, to be able to catch regressions like #45098.

This can be done in the engine or the framework. I will list some of my proposals below:

Engine:

• Use the scenario app.
  • Scenario app is currently only running on simulators. it Has to be set up running on some in house devices. The effort is tracked here: Run the Scenario App on physical iOS devices in CI  #43852
  • It decouples with framework logics and focus on the actual rendering.
  • Cannot catch framework bugs.
  • The tests run as early as engine repo post commit.

Framework

• Create an example app and run flutter driver to perform screenshot tests.
  • Also has to be set up running on some in house devices.
  • Can potentially catches framework bugs.
  • The tests run after each framework commit, engine breakages are caught late after engine roll.

We can potentially have tests set up on both framework and engine. We seems to have better infra set up to support this in the framework so we might start with a test in the framework first.