The Developer Preview for Android 11 is now available; test it out and share your feedback.

androidx.arch.core.executor.testing

Classes

CountingTaskExecutorRule A JUnit Test Rule that swaps the background executor used by the Architecture Components with a different one which counts the tasks as they are start and finish. 
InstantTaskExecutorRule A JUnit Test Rule that swaps the background executor used by the Architecture Components with a different one which executes each task synchronously.