proton-mail-android/docs/0005-use-run-blocking-test.md

Use runBlockingTest

• Status: Accepted
• Deciders: Marino, Zorica, Stefanija, Davide, Tomasz, Maciej
• Date: 10/09/2021

Context and Problem Statement

Inconstancy in test between the usage of runBlocking and runBlockingTest

Considered Options

• runBlocking
• runBlockingTest

Evaluations between runBlocking and runBlockingTest

• Both of the solutions executes all the Coroutines on a single thread
• runBlockingTest is specifically designed for test, while runBlocking has a different purpose
• runBlockingTest enables us to control the virtual time, if needed
• runBlockingTest has auto-advance features, that let's us skip the various delay() and similar that would let the tests take a considerable amount of time to be completed
• runBlockingTest helps us to verify that the Coroutines has a correct flow ( e.g. does not "get stuck" or never completes ) and does not leak
• runBlockingTest has some incompatibilities, for example with Room's Transactions

Decision Outcome

• We should use runBlockingTest as a standard
• We can use runBlockingWithTimeout when there is a incompatibility issue ( see Room's Transactions ) and the test cannot completes correctly otherwise

Consequences

1. We should replace runBlocking with runBlockingTest wherever possible
2. We should replace runBlocking with runBlockingWithTimeout when runBlockingTest cannot be used
3. Further discussion is needed for coroutinesTest