Instrument tests to write assertions over screen data

[vidya88]

@olemis commented on Apr 14

Feature description

Assertions for emulator screen data

Is your feature request related to a problem? Please describe.
During a test run it's not possible to assert that screen is rendering certain information at a given moment in time.

Describe the solution you'd like
Instrument tests to write assertions over screen data

Describe alternatives you've considered
This feature can be implemented by rendering emulator window in a bitmap and extracting the bits using image processing techniques . This might be more accurate , but is a bit more (and unnecessarily) complicated approach .

Additional context
Noticed while trying to write tests for #169 in #172 .

Possible implementation
A preliminary roasmap to get this done is as follows

• Keep internal testing context to track screen draw events including, at least , bitmaps and text.
• Make this context available to test_fsm.c unit test cases
• Implement debug messages for querying screen state without interfering with statndard firmware message processing, i.e. via usb_debug
• The former implies defining a separate debug.proto file in hw-protob (TODO: new issue)