Coroutines + Testing = ❤️
summary
Explains the design of kotlinx-coroutines-test and how to write deterministic coroutine tests using Room, LiveData builder and Retrofit fakes; shows using runBlockingTest, TestCoroutineDispatcher/TestCoroutineScope and Dispatchers.setMain to advance virtual time (2s delays, 100ms await timeout) so tests never flake. Demonstrates mock vs fake tradeoffs, a failing timeout case fixed with supervisorScope and finally emitting null, and a known bug when switching to another dispatcher with a workaround via dependency injection. Tests and sample code are runnable but the library remains experimental.
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chapters (7)
- 0:00Introduction to coroutines
- 6:52Testing coroutines with Room
- 22:33Testing ViewModel with coroutines
- 28:08Testing LiveData builder
- 33:16Testing multiple coroutines
- 40:54Library design of runBlockingTest
- 45:05Q&A and summary
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