Added KillApp command to reproduce System-initiated Process Death on Android

[galex]

Proposed Changes

This PR allows to test a screen against what is called a System-initiated Process Death which is something very specific to the Android platform, but gives a very strong proposal value to Maestro for Android developers 👍

Currently, only stopApp is available as a command to try to reproduce it but it fails to as it uses the force-stop adb command:

adb shell am force-stop <package name>

To trigger System-initiated Process Death properly, Android developers need to be able to call the kill command on adb:

adb shell am kill <package name>

I suggest doing so by adding a killApp command:

appId: com.example.app
---
- killApp

Different behaviors per platform:

• Android: Calls adb shell am kill under the hood
• iOS: Calls stopApp (synonym command) as there is no such thing as a Process Death on iOS
• Web: Calls stopApp (synonym command) as there is no such thing as a Process Death on Web

Using this new command, an Android developer can really test for this use case by doing the following:

appId: com.example.app
---
# Puts the app into the background
- pressKey: Home
# Kills the app (adb shell am kill) 
- killApp
# Relaunches the app
- launchApp:
    stopApp: false # Without adb shell am force-stop

A test to detect the Process Death issue can be found there and running it does manage to detect the issue properly:

Testing

• Added an unit test for reading a new killApp command
• Added an integration test
• Tested against a real use case in a demo project

Let me know what you think or if something missing! 😊
Thank you 🙏

[amanjeetsingh150]

@galex can you help raising PR on maestro-docs. For adding docs around what this solves and usage?

https://github.com/mobile-dev-inc/maestro-docs

[galex]

@amanjeetsingh150 Sure!