TestCoroutineRule.kt

@ExperimentalCoroutinesApi
class TestCoroutineRule : TestRule {

    private val testCoroutineDispatcher = TestCoroutineDispatcher()
    private val testCoroutineScope = TestCoroutineScope(testCoroutineDispatcher)

    override fun apply(base: Statement?, description: Description?) = object : Statement() {
        @Throws(Throwable::class)
        override fun evaluate() {
            Dispatchers.setMain(testCoroutineDispatcher)
            base?.evaluate()
            Dispatchers.resetMain()
            testCoroutineScope.cleanupTestCoroutines()
        }
    }

    fun runBlockingTest(block: suspend TestCoroutineScope.() -> Unit) =
        testCoroutineScope.runBlockingTest { block() }

}