Kotlin coroutine unit testing the better way

In the realm of Kotlin programming, unit testing code that utilizes coroutines can be challenging due to the way exceptions are handled within coroutines, often leading to unreliable test results. This document highlights a common issue where exceptions thrown inside coroutines are not propagated as test failures, providing a false impression of test success. The guide introduces the use of the kotlinx-coroutines-test library to address this issue, specifically recommending the implementation of TestCoroutineScope and its cleanupTestCoroutines() method to ensure exceptions are correctly reported as test failures. Additionally, it suggests creating a JUnit5 test extension, CoroutineTestExtension, to automate proper test configurations, thus enhancing test reliability by automatically handling coroutines exceptions and unfinished coroutines as test failures. This approach not only improves test accuracy but also simplifies the setup process, encouraging developers to adopt best practices easily.